问题描述： since和before哪个前后时态一致? 1个回答 分类：英语 2014-11-21 问题解答： 我来补答 efore 引导的状语从句,表示主句的动作发生在从句的动作之前;We cleaned the classroom before we laft school.He had been a cook before he went to college.since 引导的状语从句,主句常用现在完成时,从句常用一般过去时;We haven't seen each other since we parted. 展开全文阅读
