Unit9-English11

BÀI TẬP TIẾNG ANH LỚP 11 UNIT 9 THE POST OFFICE A. MULTIPLE CHOICES: I/ Select the synonym of the following bold and underlined word in each sentence in the unit: 1/ What services do you think the post office offers? A. believe B. see C. know D. understand 2/ Thanh Ba Post Office is equipped with advanced technology and a spacious , pretty place for transaction. A. big B. roomy C. giant D. oversized 3/ You can choose to send your letters by air or surface mail. A. have B. like C. select D. get 4/ The maximum weight limit of a parcel is 31.5 kg. A. boundary B. length C. check D. end 5/ We offer a very competitive rate for parcels of under 15kg. A. effective B. emulative C. adjective D. active 6/ We offer a speedy and secure service of transferring money in less than 24 hours. A. safe B. certain C. fast D. sound 7/ Besides the ordinary telephone call service, our Post Office provides the Messenger Call Service. A. same B. regular C. known D. right 8/ This service helps you to notify the recipient of the time and place to receive the call. A. talk B. speak C. inform D. report 9/ You want to send a document and do not want to lose its original shape? A. creative B. causal C. fresh D. primary 10/ Fax transmission has now become a cheap and convenient way to transmit texts and graphics over distances. A. transfer B. give C. take D. bring II/ Select the antonym of the following bold and underlined word in each sentence in the unit: 1/ What services do you think the post office offers ? A. withdraws B. receives C. sells D. brings 2/ Thanh Ba Post Office is equipped with advanced technology and a spacious , pretty place for transaction. A. tiny B. small C. little D. few 3/ You can choose to send your letters by air or surface mail. A. have B. throw C. cast D. receive 4/ The maximum weight limit of a parcel is 31.5 kg. A. tiny B. small C. minimum D. little 5/ We offer a very competitive rate for parcels of under 15kg. A. cooperative B. useful C. individual D. passive 6/ We offer a speedy and secure service of transferring money in less than 24 hours. A. unsure B. uninterested C. slow D. open 7/ Besides the ordinary telephone call service, our Post Office provides the Messenger Call Service. A. noteworthy B. impressive C. unusual D. irregular 8/ This service helps you to notify the recipient of the time and place to receive the call. A. miss B. deliver C. publish D. expel 1 BÀI TẬP TIẾNG ANH LỚP 11 9/ You want to send a document and do not want to lose its original shape? A. ultimate B. unproductive C. sterile D. imitative 10/ Fax transmission has now become a cheap and convenient way to transmit texts and graphics over distances. A. inopportune B. remote C. unavailable D. distant III/ Choose the best answer A, B, C or D for each sentence: 1/ I’m reading a _______ story book this week. A. differ B. difference C. different D. differently 2/ He gave her a _______ look. “Are you sure?” he demanded. A. challenge B. challenger C. challenged D. challenging 3/ It was said that the article was an excellent piece of _______ journalism. A. investigate B. investigative C. investigation D. investigating 4/ The boss informs that the company needs to reduce its _______ on just one particular product. A. depend B. dependence C. dependable D. dependant 5/ My mother's attitudes are very _______, considering her age. A. modern B. modernity C. modernize D. modernization 6/ Is it true that the sea bed _______ here to 5000 meters? A. deep B. deepens C. deeper D. depth 7/ They've got to try to keep _______ as they grow older. A. act B. active C. action D. actor 8/ That woman would never do anything to _______ the lives of her children. A. danger B. dangerous C. endanger D. endangered 9/ If our product doesn't work, the customers are given the _______ of a refund or a replacement. A. choice B. choose C. chooser D. choosing 10/ Last weekend they saw a quick film showing the various stages in the _______ of glass. A. produce B. producer C. products D. production IV/ Choose the correct words to complete the sentences: 1/ My brother said that they _______ be ashamed of themselves. A. could B. should C. did D. would 2/ The doctor is doing all that he _______, but the boy is still not breathing properly. A. can B. could C. shall D. might 3/ You _______ to have agreed to buy that MP4 player without knowing how much it would cost. A. shouldn’t B. couldn’t C. didn’t D. oughtn't 4/ Linh said she _______ see her uncle the next day. A. ought to B. should C. would D. must 5/ They say that cars _______ park in front of the entrance. A. mustn't B. didn’t have to C. couldn’t D. didn’t need 6/ Is she _______ in cash or by credit card? A. paying B. paid C. having paid D. to pay 7/ I _______ home every two weeks to tell my mother I'm fine. A. rang B. had rung C. ring D. have rung 8/ They'll pay us double _______ we get the work finished by Saturday. A. if B. unless C. supposing D. provided 2 BÀI TẬP TIẾNG ANH LỚP 11 9/ They wouldn't work for him _______ he paid them twice their current salary. A. if B. provided C. in case D. as long as 10/ I’ll ask them to buy everything you produce, _______ of course the price is okay. A. unless B. as long as C. provided D. if V/ Choose the word whose underlined part has a different pronunciation from the others in each group: 1/ A. sea B. ocea n C. chea p D. tea ch 2/ A. word B. wor k C. wor m D. world 3/ A. desks B. parks C. pays D. effects 4/ A. go vern B. so me C. po st D. mo nth 5/ A. Pacific B. Atlantic C. America n D. balance 6/ A. gu n B. hu man C. popu lation D. cu ter 7/ A. partly B. century C. luckily D. supply 8/ A. de pth B. se cret C. be tween D. pre fer 9/ A. offices B. introduces C. pollutes D. classes 10/ A. oversized B. cared C. filled D. minded VI/ Choose the word whose underlined part has a different pronunciation from the others in each group: 1/ A. undersea B. ocea n C. revea l D. brea the 2/ A. world B. wor k C. for m D. word 3/ A. tasks B. parts C. bays D. effects 4/ A. co ver B. so me C. lesso n D. to n 5/ A. Pacific B. Atlantic C. India n D. balance 6/ A. gu lf B. hu man C. popu late D. cu te 7/ A. century B. tiny C. partly D. supply 8/ A. de pth B. re fer C. be neath D. se cret 9/ A. challenges B. devices C. submarines D. passages 10/ A. moved B. killed C. required D. landed VII/ Choose the word whose main stress is placed differently from the others in each group: 1/ A. undersea B. comprehend C. overcome D. submarine 2/ A. Atlantic B. Indian C. Antarctic D. Pacific 3/ A. bottom B. starfish C. belly D. explain 4/ A. challenge B. surface C. further D. inform 5/ A. mystery B. satellite C. various D. successful 6/ A. beneath B. sample C. current D. balance 7/ A. connection B. oxygen C. animal D. oversized 8/ A. sophisticated B. independently C. biodiversity D. international 9/ A. extreme B. refer C. ocean D. surround 10/ A. investigate B. interaction C. indication D. understanding VIII/ Match the words in column A with their synonyms in column B: A B 1/ picture 2/ different A/ examine B/ stimulus 3/ cover 4/ overcome C/ dissimilar D/ spread 5/ challenge 6/ sophisticated E/ globe F/ complicated 7/ investigate 8/ indication G/ painting H/ supply 9/ contribute 10/ world I/ get over J/ evidence IX/ Match the words in column A with their antonyms in column B: A B 1/ beneath 2/ depth A/ safety B/ minor 3 BÀI TẬP TIẾNG ANH LỚP 11 3/ secret 4/ major C/ imprison D/ public 5/ clean 6/ danger E/ dirty F/ protection 7/ sparing 8/ threat G/ abundant H/ overhead 9/ release 10/ smart I/ surface J/ stupid X/ Complete the following sentences by inserting the missing Adjective clauses. Choose the Adjective clause that fits each sentence best: A B 1. The policewoman _____ is my mother’s friend. A. that ever acted on this stage 2. Hanh and Nguyen, _____ have just got married. B. which he dropped a few minutes ago. 3. That lake _____ is not very wide. C. who arrested the thief 4. We don’t have anything to do, _____. D. we crossed 5. She’s the finest woman _____ E. whom you met yesterday 6. They will visit the garage _____ before they come back home. F. which makes us bored 7. He was glad to find the wallet _____. G. where their father works 8. Mrs. Hoa, _____, is working in a hospital. H. whose daughter is a good student 9. Rooney is playing for MU, _____ I. who can answer this question 10. Is there anyone _____? J. which is a famous football club. XI/ Find the one mistake (A, B, C or D) in these sentences and then correct them: 1/ (A) I'll pay you (B) double (C) unless you get the work (D) finished by Friday. 2/ (A) There are, (B) if you don't mind me (C) to say so, one or two problems (D) with this plan. 3/ You (A) won’t pay (B) for time off (C) unless you have (D) a doctor’s note. 4/ He (A) hasn’t got (B) any hobbies—(C) if you call watching TV (D) a hobby. 5/ (A) Provided that you (B) had the money (C) in your account , you can withdraw (D) up to £100 a day. 6/ (A) We’d buy everything you produce, (B) provided (C) of course the price is (D) right . 7/ “She doesn’t think (A) she’ll get a job.” “She (B) should worry, (C) with all her qualifications (= she does not need (D) worrying).” 8/ (A) In order that training (B) should be effective (C) there must be planned (D) systematically. 9/ You (A) ought have come (B) to the meeting. (C) It was (D) interesting. 10/ (A) What do you need your own computer (B) for ? You (C) can use (D) us . XII/ Find the one mistake (A, B, C or D) in these sentences and then correct them: 1/ There are, (A) unless you don't mind me (B) saying so, one or two (C) problems (D) with this plan. 2/ (A) Unless you call me (B) saying you're not coming, (C) I'll see you (D) at the theatre 3/ (A) If Europe fails (B) to agree on this, we can (C) tell goodbye to any (D) common foreign policy. 4/ (A) If you (B) need any help, (C) please don't hesitate (D) to say. 4 BÀI TẬP TIẾNG ANH LỚP 11 5/ They (A) were wondering where (B) to hold the office party and I (C) warned the Italian restaurant (D) near the station. 6/ (A) We’d buy everything you manufacture, (B) provided (C) certainly the price is (D) acceptable . 7/ “My brother doesn’t think (A) he’ll find a job.” “He (B) should be anxious, (C) with all his education (= he does not need (D) worrying).” 8/ (A) In order that training (B) should be efficient (C) there must be intended (D) systematically. 9/ We (A) ought have come (B) to the ballet. (C) It was (D) exciting. 10/ (A) What do they need their own laptop (B) for ? They (C) can use (D) me . XIII/ Find the one mistake (A, B, C or D) in these sentences and then correct them: 1/ She (A) asked me (B) if I knew (C) whom had got (D) the job. 2/ (A) I've been meaning (B) to ask you (C) where you get your hair (D) to cut. 3/ (A) There were 500 (B) passengers, (C) whose 121 (D) drowned. 4/ She was (A) only twenty (B) when she (C) having her (D) first baby. 5/ (A) To see (B) if you can guess (C) which one is me in my old (D) school photo. 6/ The police (A) asked me (B) would explain (C) why I hadn't reported the accident (D) sooner . 7/ She lived (A) in Rome (B) for a couple of years, (C) where she taught (D) England. 8/ (A) Have you been (B) to the restaurant (C) it's just opened (D) in town? 9/ He (A) rang James, (B) who was a good friend (C) as well as the (D) doctor family. 10/ (A) Someway , that evening, (B) which I'll tell you more about (C) later , I ended up (D) staying at Rachel's place. XIV/ Read the following passage carefully, and then select the best option A, B, C or D to complete it: AUSTRIAN POST OFFICERS IN THE OTTOMAN EMPIRE Austria and other European nations maintained an extensive (1) _______ of post offices in the Ottoman Empire, typically motivated by the unreliable postal system of the Ottomans. For Austria, the (2) _______ started in 1748 with the establishment of a (3) _______ in Galata outside of Constantinople, and eventually extended to dozens of (4) _______ throughout the Balkans and the eastern Mediterranean. Beginning in 1863, (5) _______ of Lombardy-Venetia were used, but after the losses of these areas in 1867, Austria had to issue special stamps; in appearance identical to (6) _______ stamps of the period, but denominated in soldis and florins. In 1886 this was changed to paras and piasters to match Turkish money, (7) _______ by surcharging the existing stamps of the offices, then regular Austrian stamps. Stamps printed specifically for the offices resumed in 1906, by using Austrian stamps (8) _______ the denomination (at this point the denomination of Austrian stamps was printed in a second step), and the Jubilee issue of 1908 included the same (9) _______ denominated in piasters. While early issues are not common, the volume of mail by the end of the empire was such that both used and unused stamps are still commonly (10) _______. + New words: - denominate (v.): cho tên là, gọi tên là, đặt tên là. - florin (n.): đồng florin (đồng hào của Anh bằng 2 silinh). - piaster (n.): đồng bạc (tiền Tây Ban Nha, Ai Cập, Thổ Nhĩ Kỳ). 5 BÀI TẬP TIẾNG ANH LỚP 11 - surcharge (v.): 1. Chở/ chất quá nặng; bắt phạt quá nặng; đóng thuế quá nặng. - jubilee (n.): lễ kỉ niệm 50 năm; dịp vui mùa mở hội. 1/ A. way B. method C. system D. network 2/ A. purchase B. sale C. practice D. service 3/ A. school B. post office C. factory D. company 4/ A. regions B. areas C. houses D. locations 5/ A. stamps B. books C. things D. pictures 6/ A. American B. Austrian C. European D. Asian 7/ A. first B. second C. next D. last 8/ A. having B. removing C. releasing D. missing 9/ A. designs B. shapes C. forms D. images 10/ A. alive B. new C. fresh D. available XV/ Read the following passage carefully, and then select the best option A, B, C or D to complete it: Approximately one-third of the Arctic (1) _______ is underlain by continental shelf, (2) _______ includes a broad shelf north of Eurasia and the narrower shelves of North America and Greenland. Seaward of the continental shelves (3) _______ the Arctic Basin proper, which is subdivided (4) _______ a set of three parallel ridges and four basins (also (5) _______ as deeps). These features were discovered and explored (6) _______ in the late 1940s. The Lomonosov Ridge, the major ridge, cuts the Arctic Basin (7) _______ in half, extending as a submarine bridge 1,800 km (1,100 mi) (8) _______ Siberia to the northwestern tip of Greenland. Parallel (9) _______ it are two shorter ridges: the Alpha Ridge on the North American (10) _______, defining the Canada and Makarov basins, (11) _______ the Arctic Mid-Ocean Ridge on the Eurasian side, (12) _______ the Nansen and Amundsen basins. The average (13) _______ of the Arctic Ocean is only 1,300 m (4,300 ft) (14) _______ the vast shallow expanses on the continental shelves. The deepest (15) _______ in the Arctic Ocean is 5,450 m (17,880 ft). New vocabulary: - to underlie- underlay- underlain (v.): nằm dưới, ở dưới - seaward (n.): hướng biển; (adv.): về hướng biển - to subdivide (v.): chia nhỏ ra - ridge (n.): chóp, chỏm, ngọc, đỉnh (núi) - basin (n.): chỗ trũng, lòng chảo; (địa chất) lưu vực; vịnh nhỏ - tip (n.): đầu, đỉnh, chóp - expanse (n.): dải, dải rộng (đất .) 1/ A. Sea B. Ocean C. Lake D. River 2/ A. it B. whom C. that D. which 3/ A. is B. lies C. runs D. stands 4/ A. on B. in C. into D. onto 5/ A. known B. considered C. thought D. remembered 6/ A. starting B. beginning C. appearance D. creation 7/ A. most B. mostly C. all D. almost 8/ A. in B. at C. from D. between 9/ A. to B. of C. with D. by 10/ A. shape B. face C. size D. side 11/ A. and B. but C. or D. so 12/ A. forming B. coming C. defining D. making 13/ A. height B. depth C. width D. length 14/ A. by B. with C. in spite of D. because of 15/ A. mark B. area C. place D. point B. USE OF ENGLISH: 6 BÀI TẬP TIẾNG ANH LỚP 11 I/ Match the sentences, clauses or phrases in column A with the ones in column B to make meaningful sentences: A B 1/ The doctor _____ is my mother’s friend. A/ which bores them. 2/ Mr. Nam and Ms. Nga, _____ have just traveled to Bangkok. B/ who can help me with these difficult questions 3/ The street _____ is not very wide. C/ which she left in her room this morning. 4/ My friends have nothing to do, _____. D/ who cured my brother well 5/ Tom Cruise is a handsome man _____ E/ which is a famous football club in Italy. 6/ Her classmates will visit the zoo _____ after they have finished the exam. F/ that ever acted in many films. 7/ She was glad to find the handbag _____. G/ where there are a lot of fun animals 8/ Mr. Minh, _____, is working in a very big company. H/ whom we met yesterday morning 9/ Ronaldo is now playing for AC Milan, _____ I/ whose daughter is my classmate 10/ There isn’t anybody _____, is there? J/ we are riding along II/ Supply the correct form of the word in brackets: 1/ He suffers from a (nerve) _______ disorder. 2/ I worry about the (destruct) _______ effect that violent films may have on children. 3/ (Mystery) _______, the light came on, although no one was near the switch. 4/ The river froze to a (deep) _______ of over a meter. 5/ Children are encouraged to take an (investigate) _______ approach to learning. 6/ Disneyworld is one of Florida's major (tour) _______ attractions. 7/ Tyler is remarkably (world) _______-wise for such a young girl. 8/ He never goes out without his security men in (attend) _______. 9/ There's not enough (interact) _______ between the management and the workers. 10/ Commodity prices can be a useful (indicate) _______ of inflation, he claimed. III/ Supply the correct form of the word in brackets: 1/ It was too dark to read our map and we took a wrong (turn) _______. 2/ The book was delivered yesterday with a note (say) _______ the bill for it would follow in a day or two. 3/ As (chair) _______ of the association, he held office for over twenty years. 4/ Such unpopular legislation is unlikely to be introduced before the next (elect) _______. 5/ She sent a message with John (say) _______ that she couldn't come. 6/ The company was set up to buy and sell shares on behalf of (invest) _______. 7/ The police said that it was the blow that (deliver) _______ to her head that had killed her. 8/ "If you like I can do some (shop) _______ for you." "That's a very kind offer." 7 BÀI TẬP TIẾNG ANH LỚP 11 9/ I'd been away for a few days so I had a lot of post (wait) _______ for me. 10/ The (major) _______ of people in the town strongly support the plans to build a by-pass. IV/ Complete the second sentence so that it has a similar meaning to the first one, using the word in brackets: 1/ You might win $ 1500, and then you’d travel to Singapore. (if) → You’d travel _______________________________________ $ 1500. 2/ Our electric fan is not working properly and we feel hot. (would) → If our ______________________________________________ so hot. 3/ Her brother should give up smoking to protect his health. (would) → If he _____________________________________ improve his health. 4/ Perhaps my family would go to Hue to visit our grandparents. (went) → If my family ____________________________ visit our grandparents. 5/ I think you should not talk too much in class. (you) → If I _______________________________________________ in class. 6/ His sister doesn’t speak English well enough to work for that foreign company. (better) → If his sister ___________________________ for that foreign company. 7/ My roommates don’t have enough money so they can’t travel to Nha Trang. (could) → If my roommates __________________________________ Nha Trang. 8/ We’re not as rich as Rockefeller so we can’t buy a big house here. (were) → If we ________________________________________________ here. 9/ I won’t go out if it doesn’t stop raining. (unless) → I won’t _____________________________________________ raining. 10/ She wouldn’t write unless she heard some news. (if) → She wouldn’t _____________________________________ some news. V/ Supply the correct verb tense, paying careful attention to the tense sequence: 1/ If war (come) _______, the people in the nation will be ready. 2/ If today (be) _______ Sunday, I should not have to go to school. 3/ If we don’t study our lessons, we (not have) _______ good marks in the exam. 4/ If he had had her address, he (write) _______ to her. 5/ You (catch) _______ cold if you went out in the rain. 6/ If the weather is fine, we (go) _______ to the mountain. 7/ If he (write) _______ more carefully, he might not have made so many mistakes. 8/ Were she to speak to him like that, he (be) _______ very angry. 9/ Supposing your sister (see) _______ you going to the concert with me, what might she think? 10/ If it (be) _______ convenient, let’s meet at the park. VI/ Supply the correct verb tense, paying careful attention to the tense sequence: 1/ I'll pay you double if you (get) _______ the work finished by Friday. 2/ We'll have the party in the garden if the weather (be) _______ good. If not, it'll have to be inside. 3/ If anyone (ring) _______ for me, please tell them I'll be back in the office at 4 o'clock. 4/ If she hadn't called, I (not know) _______. 5/ I wouldn't work for them (even) if they (pay) _______ me twice my current salary. 6/ We'll deal with that problem if and when it (arise) _______. 7/ If disturbed, the bird (abandon) _______ the nest, leaving the chicks to die. 8 BÀI TẬP TIẾNG ANH LỚP 11 8/ Unless you (call) _______ me to say you're not coming, I'll see you at the theatre. 9/ "Jacinta (be) _______ there with her boyfriend." "Which one? She's got several." 10/ It's either Spanish or Portuguese that she (speak) _______, but I've forgotten which. VII/ Complete the following sentences, using “WILL, WOULD, SHOULD, CAN, COULD, MAY, MIGHT, DON’T, DOESN’T, WAS”. Each word is used only once: 1/ We tried phoning them but there _______ no answer. 2/ The coach leaves at 8.58, so we _______ be in Scotland by lunchtime. 3/ Why _______ we have lunch together on Sunday morning? 4/ He _______ be ashamed of himself as he has done something wrong. 5/ She brought me some juice because she thought I _______ be thirsty. 6/ Do the best you _______ - We realize the circumstances are not as ideal as we think. 7/ He knew there _______ be trouble unless the report was finished by 5pm. 8/ _______ she look lovely in that new dress and that colorful hat? 9/ I know that the cause of the accident _______ never be discovered. 10/ When my brother was younger he _______ stay up all night and not feel tired. VIII/ Rewrite the sentences using the word in brackets, beginning as shown: 1/ There’s no point in asking her to kelp. (worth) → It ______________________________________________ her to help. 2/ Thu couldn’t get her teacher’s permission to be absent yesterday. (let) → Thu’s teacher _____________________________________ yesterday. 3/ “Where are you going tomorrow, Hanh?” asked Nguyen. (where) → Nguyen asked ____________________________________________. 4/ Lan’s behavior at the wedding party annoyed me. (Lan) → I was ___________________________________ at the wedding party. 5/ It’s very kind of you to have lent me some money or I would have had to borrow my classmates. (you) → I would have had _______________________________ some money. 6/ Mai didn’t listen to what her mother told her. (notice) → Mai took ___________________________________________ advice. 7/ The students had to finish the homework and write an assignment as well. (addition) → The students had to _____________________________ an assignment. 8/ When Maradona was a child, he played football almost every day. (his) → Maradona played football ____________________________________. 9/ Let’s visit the National park this morning. (go) → Why _________________________________________ this morning? 10/ Long found it difficult to concentrate on his lesson because of the noise. (difficulty) → Long ____________________________________ because of the noise. IX/ Read the sentences below carefully, and then put them in the correct order to make a meaningful reading: (Number 1 and number has done first for you) 1/ Cleveland is the county seat of Cuyahoga County, the most populous county in the U.S. state of Ohio. 2/ Recent investments have provided the city with tourist attractions in the downtown area, such as Jacobs Field, the Rock and Roll Hall of Fame, and Playhouse Square Center. 3/ With the decline of heavy manufacturing, Cleveland's businesses have diversified into the service economy, including the financial services, insurance, and healthcare sectors. 9 BÀI TẬP TIẾNG ANH LỚP 11 4/ Nevertheless, the city faces continuing challenges, in particular from concentrated poverty in some neighborhoods and difficulties in the funding and delivering of high- quality public education. 5/ It was founded in 1796 near the mouth of the Cuyahoga River, and became a manufacturing center owing to its location at the head of numerous canals and railroad lines. 6/ In studies conducted by The Economist in 2005, Cleveland and Pittsburgh were ranked as the most livable cities in the United States, and the city was ranked as the best city for business meetings in the continental U.S. 7/ As of the 2000 Census, the city proper had a total population of 478,403, making it the 33rd largest city in the nation. X/ Read the sentences below carefully, and then put them in the correct order to make a meaningful reading: (Number 1 and number 12 have done first for you) 1/ Tsunami, Japanese word meaning “harbor wave,” used as the scientific term for seismic sea waves that can cause catastrophic damage when they hit a coastline. 2/ Since 1819, about 40 tsunamis have struck the Hawaiian Islands. 3/ Tsunamis can be generated by an undersea earthquake, an undersea landslide, the eruption of an undersea volcano, or by the force of an asteroid crashing into the ocean. 4/ When the ocean floor is uplifted or offset during an earthquake, a set of waves is created similar to the concentric waves generated by an object dropped into the water. 5/ The most frequent cause of tsunamis is an undersea earthquake. 6/ Most tsunamis originate along the Ring of Fire, a zone of volcanoes and seismic activity, 32,500 km (24,000 mi) long, which encircles the Pacific Ocean. 7/ A tsunami can have wavelengths, or widths (the distance between one wave crest to the next), of 100 to 200 km (60 to 120 mi), and may travel hundreds of kilometers across the deep ocean, reaching speeds of about 725 to 800 km/h (about 450 to 500 mph). 8/ People onboard a ship passing over it would not even notice the tsunami. 9/ A tsunami is not one wave but a series of waves. 10/ Upon entering shallow coastal waters, however, the waves suddenly grow rapidly in height. 11/ In the deep ocean, the waves may be only about half a meter (a foot or two) high. 12/ When the waves reach the shore, they may be 15 m (50 ft) high or more. 10