The Adverbial Clause ( 状语从句 )1 、时间状语从句： 从属连词有： when, while, as, whenever, before, after, since, till, until, as soon as, once… 等。注意：（ 1 ） when, as, while when 既可引导持续性动作，又可引导短暂性动作。它表示动作同时发生，或从句的动作发生在主句动作之前。 as 引导持续性动作，侧重主句和从句的动作同时发生。e.g. He sang as he walked. While ：指的是“在某一时间里”，“在…期间”，从句里的动作必须是持续性的，它也强调主句和从句动作的同时发生，往往侧重主句和从句动作的对比。e.g. While we were watching TV, he was writing a composition. while 也可做并列连词，表示对照的意思。如：e.g. He is tall while his brother is short. 当 when, as, while 表示“在…一段时间里”，主从句的动作同时发生时，可以换用。如： e.g. While (When 或 As) we were discussing, Mr. Smith came in.注意： （ 2 ）… as soon as… =The moment/minute/second/instant… =No sooner ..than../ Hardly…when../ Scarcely…when.. =directly/immediately/instantly =On/Upon sth./ doing…注意： （ 3 ） Beforee.g. I had waited long before she came. It won’t be long before she comes back. They hadn’t been married a month before they quarrelled.since 表从过去某一时间或动作、事情起到目前为止，“自… . 以 来”句型：It is (has been)…..+ since + 一般过去时e.g. It is five years since I began to learn English.注意： （ 4 ） since ① 肯定句中，主句用持续动词，表示“直到…为止”。e.g. I worked till (until) he came back. ② 否定句中，主句用瞬间动词，表示“直到…才”。e.g. I didn’t go to bed until (till) he came back.注意： （ 5 ） till/until句首一般用 until 。Each/every time…Last/next time…The first time…By the time…注意： （ 6 ） 由 where, wherever, anywhere, everywhere 引导2 、地点状语从句：由 because, as, since, now that 引导。区别是 : because ：表示“因为”，直接而明确的原因和理由，语气最强， why 提问的句子，一般...
