61840 time expressions with the past perfect
Time adverbs used with the present perfect tense
Coming to terms with the past in postwar literature and philosophy
UNIT 5 THE PAST PERFECT & THE PAST SIMPLE
Changing a sentence into the passive when the active verb is in the past perfect tense
Thì quá khứ hoàn thành thì quá khứ hoàn thành tiếp diễn (the past perfect the past perfect continuous)
17389 the past perfect continuous tense