... 1,000,000,000 a/one hundred, thousand, million, billion c. 101 1,001 etc. a/one hundred and one, a/one thousand and one d. 201 2,001 etc. two hundred and one, two thousand and one 2. Ordinal Numbers ... subject and the be-verb from the adverb clause. If there is no be-verb clause, then omit the subject and change the verb to the –ing form. 13 UNIT THREE UNIT THREEUNIT THREE UNIT THREE: ... it demands a lot of concentration. o demand n [C or U] a need for something to be sold or supplied: supply and demand. o demanding adj, needing a lot of time, attention or energy: a demanding...