高中英语语法专项讲义：状语从句

状语从句 一 时间状语从句 1． 当when引导时间状语从句时，从句的动作可以与主句的动作同时进行，用while或as代替；也可以略先于主句动作，用as soon as代替；也可以略后于主句的动作，用before代替。 I like perfect quietness when I am working. When they arrived，it started to rain. The train had left when he hurried to the station. 有时when引导的时间状语从句，在意义上与主句是并列关系，when相当于and then或and suddenly，它与主句之间常用逗号分开。 I stayed till noon，when I went home. I was taking a walk，when I came across a friend of mine. when引导从句有时具有让步、原因的意义。 He usually walks when he might ride. Why did not you do it when you knew it would do you good？ 2． 当主句的谓语是现在完成时或过去完成时时，表示“自从…以来”的时间状语从句用连词since引导，不能用after。若用after引导从句，则主句中的谓语不能用完成时。 He has been abroad since he graduated from the university. He went abroad after he graduated from the university. since从句中的谓语根据具体情况可以用一般过去时或现在完成时。 I have known her since we were children. I have known her since I have lived in this street. 3． the moment，the minute，the instant和the second均可以用作连词，解作“一…（就）”，相当于as soon as。 The moment I saw you I knew you were angry with me. I will tell her the minute she gets here. I loved you the instant I saw you. The second he heard the news，he told it to me. 4． 在英国英语中，immediately，instantly和directly均可以用作连词，解作“一…（就）”，相当于as soon as。 Immediately his intentions are understood，he may leave. I recognized her instantly I saw her. Directly I had done it，I knew I had made a mistake. 二 地点状语从句 当where和wherever用作连接副词时，前者解作“在（到）…地方”，后者解作“无论在（到）哪里”。 Where there is a will，there is a way. Wherever he goes，he is welcome. 三 原因状语从句 1． 用because引导的原因状语从句往往回答why的问题，语气最强，通常放在主句之后，但是在现代英语中也可以放在主句之前。since和as所引导的原因状语从句不回答why的问题，语气要比because弱，通常放在主句之前。since比as稍微更正式一些，它所引导的从句的内容往往对方已经知道，解作“既然…”。for是并列连词，语气最弱，通常放在主句之后，它所陈述的理由只是起补充说明作用。 He cannot come to help us now because he is busy with some other work. As you are tired，you had better have a rest. Since you ask，I will tell you. It must have rained last night，for the ground is wet. 有时用because和as都可以，但是侧重点不同：用as时，强调的是主句部分；用because时，强调的是从句部分。 As my secretary is away at present，I have a