since引导什么从句主句用现在完成时

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：

prep.自从;自…以后;从…以来;(表示气愤)何曾，什么时候。

conj.因为;由于;既然;从…以后;自…以来。

adv.自…以后;从…以来;此后;后来。

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。