复句Complex Sentence 有从句+主句的结构，从句是把一个句子改造成名词、形容词、副词类，放到主句中。
合句Compound Sentence 就是两个平等、对称的简单句，中间and, but, or连接。
- Something is strange.
- That he didn’t show up on time is strange.
- It is strange that he didn’t show up on time.
- The defendant said that he didn’t do it.
- This is decided by whether the tumor is malignant or not.
- 介词后面不能用连接词，可以用whether(which代名词 + either)
- The important thing is that we’re all right.
- The stroy that he once killed a man might just be true.
- I am afraid that I can’t help you. 其实是I am afraid the thing that I can’t help you的省略
- I know who you are. 改成非疑问句
- Babylon is what is now Baghdad. 名词性，不能用where
- I can’t tell whether/if he’s telling the truth or not.
- because: because he needs the money, he works hard.
- now that: There’s nothing to worry about, now that father is back.
- so <adj.> that: He looked so sincere that no one doubted his story. 表示结果，形容词导致的结果。
- so that: The mother locked the door from the outside, so that the kids couldn’t get out when they saw fire.
- so that: The mother locked the door so that the kids wouldn’t swallow any by mistake.
- in order that:
- lest: I’ve underlined the key points, lest you miss them. 以免（反向的目的）
- in case: You’d better bring more money, in case you should need it. 万一
- though: The witness said this, though he didn’t really see it.
- Whether= no matter
- Whoever= no matter who
- However= no matter how
- As far as: As far as money is concerned, you needn’t worry. 在xx方面
- in that: == in the sense that 某种意义来说 Picasso was a revolutionary in that he broke all traditions.意义加限制，不是真的革命
- as: He played the piano as Horowitz would have. 如何弹，像xxx
- as if: He writes as if he is left handed.
- if: If he calls, I’ll say you’re sleeping
- as long as: He won’t have it his way, as long as I’m here. 前面是一个祈使句，让这件事情按他的方式发生
- suppose: Suppose you were ill, where would you go?