问题描述： since前面加什么时态,后面又加什么时态? 1个回答 分类：英语 2014-11-05 问题解答： 我来补答 since从句中用一般过去时,主句中用现在完成时.如; He has published several books since he came here in 2009. 展开全文阅读
