定义 / 说明
像 it 和 there 这样的词可以让句子衔接更自然。it 常回指前文已提到的事物或概念，避免重复名词。there 常用于引入“某物存在”，如 There is a problem。这些词本身信息量不大，但能让英语表达更连贯，口语和写作都很重要。
关键规则
- 用 it 回指已知事物、想法或情境：I bought a phone. It was cheap.
- 用 there is / there are 表示“存在”。
- 如果指代清楚，不要反复重复同一名词。
- it 还可用于天气、时间、距离：It is raining. It is late.
- 本语法点里的 there 主要是“存在引入词”，不同于地点副词意义。
例句
- I bought a phone. It was cheap. - 我买了一部手机，它很便宜。
- There is a problem, but it is small. - 有个问题，但不大。
- There are two chairs in the kitchen. - 厨房里有两把椅子。
- I like this song. It is beautiful. - 我喜欢这首歌，它很好听。
- It is cold today. - 今天很冷。
常见错误
- ❌ I bought a phone. The phone was cheap. -> ✅ I bought a phone. It was cheap.
- ❌ It is a problem in the room. -> ✅ There is a problem in the room.
- ❌ There is cold today. -> ✅ It is cold today.