100 câu trắc nghiệm Thì quá khứ hoàn thành tiếp diễn (Past Perfect Continuous) có đáp án
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What are the auxiliary verbs of the past perfect continuous tense?

49/100

What are the auxiliary verbs of the past perfect continuous tense?

has been

had been

was being

have been

Giải thích

Chọn đáp án: B