since的用法主要有两点:一是表示”自....以来“, 二是表示”既然”之意。但如果只了解词的含义，而不了解其用法,在使用时就会造成错误。例如: | have not heard from him since | lived in  Shanghai.

(1)接时间点:如 I have stayed in that country since 1995. 要求:谓v.用现在完成时，而且须是延续性动词。
(2)接一段时间 + ago:如 They have lived in that house since two years ago. 要求:谓v.用现在完成时，而且须是延续性动词。
(3)接时间状语从句:如 I have loved her since I met her last time. / Lily has stayed at home since she left school. 要求:主句的谓v.用现在完成时，而且须是延续性动词;从句的谓v.用一般过去时，而且须是终止性动词。
(4)用于句型“It’s / It has been + 一段时间 + since + 时间状语从句”中，译作“自从…以来, 已经…(时间)了”。如 It’s / has been three months since he moved to this city. 要求:主句的谓v.用一般现在时或现在完成时;从句的谓v.用一般过去时，而且须是终止性动词。
(5)用于句型“一段时间 + has passed since + 时间状语从句”中，译作“自从…以来, …
(时间)已经过去了”。如上个例句还可写成:Three months has passed since he moved to this city. 要求:主句的谓v.用现在完成时，而且动词必须是has passed;从句的谓v.用一般过去时，而且须是终止性动词。
(6)注:当since用于否定句时，主句的谓v.可以是终止性动词。如 He hasn’t seen the film since last month.
(7)相关词组:“从那时起”:ever since、since then、from then on.
注:ever since作为一个词组，放句尾可单独使用。如I have given up smoking ever since. 另外，还可在since后接句子。since前加ever，只是加重语气而已。如 I have given up smoking ever since I caught a bad cough.
(8) since还可引导原因状语从句，译作“由于;因为”，相当于because。如 Since he was lazy, he didn’t finish his homework.