since中的时态

　　一、since通常搭配的时态

　　当since表示“自从”时，不管它是用作介词、连词还是副词，它通常都要与现在完成时连用。

　　I've worn glasses since my childhood.

　　我从小就戴眼镜。

　　The works have been closed since January.

　　一月份以来这些厂就关闭了。

　　He's put on a lot of weight since he gave up smoking.

　　他戒烟后体重增加了许多。

　　有时连用现在完成进行时。如：

　　He has been working since noon.

　　他从中午就开始工作了。