100 câu trắc nghiệm Thì quá khứ hoàn thành tiếp diễn (Past Perfect Continuous) có đáp án
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When police were investigating the road accident, they

22/100

When police were investigating the road accident, they discovered that the driver ________ two road accidents before.

had been involved in

had been being involved in

has been involved in

were involved in

Giải thích

Chọn đáp án: A