- 条件句最基础的三种：零型讲普遍事实，第一型讲有可能发生的将来，第二型讲不太可能的假设。
- 判断用第一型还是第二型，看这件事「有可能发生」还是「不太可能/纯假设」——win 和 won the lottery 是经典对比。
- 第一型除了 if，还能换成 unless/as long as/as soon as/in case，结构不变。
- if 后面接 be 动词，正式写法全部人称用 were，口语说 was 也很常见，两种都对。
- B1 核心句型，例句贴近日常生活，写作口语都用得上。
重点内容
条件句基本概念
条件句由两部分组成：
- if clause：说明条件
- main clause：说明结果
语序可以互换，意思不变：
- If you study hard, you will pass your exams.
- You will pass your exams if you study hard.
零型条件句（Zero Conditional）
用途：说一般事实、科学定律、规律——只要条件成立，结果一定发生。
结构：if/when + present simple >> present simple
- If I drink too much coffee, I can't sleep at night.（每次喝太多咖啡就睡不着）
- Ice melts if you heat it.（加热冰就融化——科学事实）
- When the sun goes down, it gets dark.（太阳一下山就天黑）
可以用 *when* 替换 *if*，意思一样。
第一型条件句（First Conditional）
用途：说未来真实或有可能发生的情况。
结构：if/when + present simple >> will + infinitive
- If it doesn't rain tomorrow, we'll go to the beach.（明天没下雨的话就去海滩）
- Arsenal will be top of the league if they win.
- When I finish work, I'll call you.
除了 *if*，还可以搭配这些词，结构一样：
| 连接词 | 例句 |
|---|---|
| unless（除非） | I don't want to stay unless I get a well-paid job. |
| as long as（只要） | You can go, as long as you're back by midnight. |
| as soon as（一……就） | I'll leave as soon as the babysitter arrives. |
| in case（万一） | I'll give you a key in case I'm not at home. |
第二型条件句（Second Conditional）
用途：说现在或未来不太可能或不现实的假设情况。
结构：if + past simple >> would + infinitive
- If we had a garden, we could have a cat.（我们没有花园，所以养不了猫）
- If I won a lot of money, I'd buy a big house.（假设性，现实里不太可能）
- I wouldn't worry if I were you.
if + be 动词的特殊用法： 语法上 *if* 后面接 be 动词，所有人称正式写法都用 were（虚拟语气），但口语里 *was* 也很常见：
✅ If I were you, I wouldn't mention it.（正式/书面） ✅ If she was prime minister, she would invest more in schools.（口语常见） ✅ He would travel more if he was younger.（口语常见）
快速对比三种条件句
| 类型 | 结构 | 用途 |
|---|---|---|
| 零型 | if + present simple >> present simple | 普遍事实、定律 |
| 第一型 | if + present simple >> will + infinitive | 未来真实可能 |
| 第二型 | if + past simple >> would + infinitive | 现在/未来不现实假设 |
例句练习
| 英文 | 中文 | 类型 |
|---|---|---|
| If you heat water to 100°C, it boils. | 水加热到 100 度就沸腾。 | 零型 |
| If it rains tomorrow, I'll take the car. | 明天下雨的话我就开车去。 | 第一型 |
| If I lived closer to the cinema, I would go more often. | 如果我住得离戏院近一点，我会更常去。 | 第二型 |
| I'll leave as soon as the babysitter arrives. | 保姆一到我就走。 | 第一型（as soon as） |
| I wouldn't worry if I were you. | 如果我是你，我不会担心的。 | 第二型 |
常见错误
❌ If it will rain tomorrow, I'll stay home. ✅ If it rains tomorrow, I'll stay home.
第一型条件句，if clause 里用 present simple，不用 will。
❌ If I would have more money, I would travel more. ✅ If I had more money, I would travel more.
第二型 if clause 用 past simple（had），不用 would have。
❌ 分不清第一型和第二型
判断方法：说的事情有可能发生 → 第一型（will）；说的事情不太可能/假设 → 第二型（would）。
- If I win the lottery, I'll buy a car.（买彩票有可能赢，第一型）
- If I won the lottery, I'd buy a car.（说自己不太可能赢，第二型）
Sources
British Council – Learn English: