专题13 状语从句-备战2021年高考英语基础语法专项训练

专题13状语从句的基本用法 一、状语从句的连词： 1. 时间状语从句的连词when, while, as, once, the time, until, before, after, as soon as, instantly。 1) when在用的时候，即可以接段时间，又可以接点时间; 有时候还能用来表示微弱的原因。 They stood respectfully when he entered the room. I couldn't very well say no when there was no one else she could ask. They figured why they should labor when there was no payoff. 2) While 表示在什么期间，一般连接延续的段时间，这时可以用when去替换。 I get the house all shipshape while he is away. While Mary was writing a letter, the children were playing outside. 但是它还可以用来表示微弱的让步状语从句，不能用when替换。 While I admit that there are problems, I don't agree that they cannot be solved. 3) As可以用来代替when和while,表示当什么的时候， I saw Peter as I was getting off the bus. As time passed, things seemed worse. 但是它可以用来去表示方式、原因、让步、对比等，不能用when, while替换。 We’d better leave the things as they are until the police arrive. We asked Phillip to come with us, as he knew the road. Try as she might, she couldn’t get the door open. Helen comes to visit us as often as she can. 4) Once,表示一旦，