Question

【题目】he boys followed the marks that they ________, until finally they found their way back to the campsite.

A. left B. have left

C. had left D. have been left

Answer 1

【答案】C

【解析】句意：男孩们沿着他们之前留下的脚印直到他们找到回到营地的道路。根据句意可知他们留下脚印是之前完成的事情，故使用过去完成时。故C正确。