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1、时间状语从句中since的用法讲解_时间状语从句中since的用法讲解(1)since表示自某一时间点以来，常与完成（进行）时态连用，强调时since前面可加ever,主句一般用 延续性动词。如用非延续性动词时必须强调动作的频率或多次、多个。Great changes have taken place since you left this city.自你离开该市以来，发生了很大的变化。I have returned home twice since I settled down in the States.自从我定居美国以来回过两次家。（不可说I have returned home sin
2、ce I settled down in the States.)(2)Itis .since 和 It has been .since.可以互用， 口语中常用前者。其句意取决于从句的谓语动词是否 可延续。since引导的从句的谓语动词若是延续性动词，常理解为某一状态的终止;若是终止性动词，则理解为某一动作的开始。It is three years since the war broke out.自战争爆发以来有三年了。It is three years since I smoked a cigar ( = since I stopped smoking a cigar).我不吸烟有三年了。 如果译成 我吸烟有三年了 ，应为:It is three years since I began to smoke.第 2 页 共 2 页