Question

since从句的时态

Answer 1

since引导时间状语从句时，从句动词通常用一般过去时，主句动词用现在完成时。
since引导原因状语从句对时态没有特殊要求。可以是过去时也可以是过去完成时，如果是过去时它的从句用现在完成时，如果是过去完成时它的主句用过去时。

扩展资料

　　She's been using since she was 13.

　　她从13岁起就吸毒。

　　His quality of life has improved dramatically since the operation.

　　手术后他的生活质量大大改善了。

　　It's a long time since they left.

　　他们已经离开很久了。

　　It's been two weeks now since she called.

　　她到现在已经有两个星期没来电话了。

　　I had been out since I was 17.

　　我从17岁起就公开我是同性恋。