状语从句是英语语法中的重要句型，连词的选用关键，可以表达不同的意思。时间状语从句的连词包括"When", "While", "As soon as", "Before", "After"等。原因状语从句的连词有"Because", "Since", "As", "Considering that"等。条件状语从句的连词有"If", "Unless", "Provided that", "In case"等。方式状语从句的连词有"As", "As if/As though", "In the way that", "Just as"等。这些连词在写作中的灵活运用可以使文章更加丰富有趣。
1. 时间状语从句
时间状语从句用来表示主句中的动作发生的时间，常用的连词有：
- When：当……的时候（表示一般的过去或将来的时间） 例如：I was reading a book when she came in.
- While：当……的时候（表示两个动作同时发生） 例如：I was reading a book while he was watching TV.
- As soon as：一……就…… 例如：As soon as she saw me, she waved her hand.
- Before：在……之前 例如：I will finish my homework before I go to bed.
- After：在……之后 例如：He went to bed after he finished his homework.
2. 原因状语从句
原因状语从句用来表示主句中的动作发生的原因，常用的连词有：
- Because：因为 例如：I am happy because I got a good grade.
- Since：因为（表示已知的事情） 例如：Since you are here, let's have dinner together.
- As：因为（表示两个事情同时发生） 例如：As it was raining heavily, we stayed at home.
- Considering that：考虑到 例如：Considering that it is too late, we'd better leave now.
3. 条件状语从句
条件状语从句用来表示主句中的动作发生的条件，常用的连词有：
- If：如果 例如：If it rains, I will stay at home.
- Unless：除非 例如：I won't go to the party unless she comes with me.
- Provided that：只要 例如：You can take the book home provided that you return it on time.
- In case：万一 例如：Take your umbrella in case it rains.
4. 方式状语从句
方式状语从句用来表示主句中的动作的方式，常用的连词有：
- As：正如 例如：As he said, he will come back tomorrow.
- As if/As though：好像 例如：He looked at me as if he didn't believe what I said.
- In the way that：以……的方式 例如：I did it in the way that you taught me.
- Just as：正当……的时候 例如：Just as I was about to leave, my friend called me.
