100 câu trắc nghiệm Thì quá khứ hoàn thành tiếp diễn (Past Perfect Continuous) có đáp án
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By the time we found the dog, it ________ (wander) in the forest for days.

83/100

By the time we found the dog, it ________ (wander) in the forest for days.

wandered

has been wandering

had wandered

had been wandering

Giải thích

Chọn đáp án: D