by which time during which time since when from where的详细用法、以

（1）by which time 引导定语从句,表示“到那个时候为止”。（2）during which time引导定语从句,表示“在那期间“。（3）since when引导时间状语从句。（when在这里作介词。注意了,when作介词时只有两种用法,就是since when和until when。）如：Until when can you saty?你可以待到什么时候?Since when have you got a new job?你从什么时候开始有了一份新工作?（4）from where引导定语从句。可以换成from which。有人说from where似乎接的是大概的地点,from which接的是具体的地点。不明白的再问哟,请及时采纳,多谢!