100 câu trắc nghiệm Thì quá khứ hoàn thành tiếp diễn (Past Perfect Continuous) có đáp án

Martha ________ three miles a day before she broke her leg

63/100

Martha ________ three miles a day before she broke her leg

walked

is walking

has been walking

had been walking

Giải thích

Chọn đáp án: D