100 câu trắc nghiệm Thì quá khứ hoàn thành tiếp diễn (Past Perfect Continuous) có đáp án
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She ________ (study) for three hours before she took a break.

77/100

She ________ (study) for three hours before she took a break.

studied

has been studying

had been studying

was studying

Giải thích

Chọn đáp án: C