By the time +过去时,主句用过去完成时 若加一般现在时,主句用现在完成时.若加现在的时间,主句用have done
问题描述：
By the time +过去时,主句用过去完成时 若加一般现在时,主句用现在完成时.若加现在的时间,主句用have done
答
过去完成时表过去的过去 By the time we reached home,He had left.Before the meeting started,he had left.现在完成时表对现在产生了影响I have learned many words in the last few years加现在的时间 应该可用I ...