最近，在刚结束的语法专项班中，我们复盘了 if 条件句。课堂中发现，很多孩子记住了will、would和 had done，却依然有时不会判断该用其中哪一种。究其原因，往往不是孩子「公式没背熟」，而是没有看清两个关键信息：

1时间：这件事发生在过去、现在还是将来？

2可能性：真实可能、不太可能还是已经无法改变？

定 义

描述将来真实、合理并且有可能发生的条件及结果。

结 构

通常为「If＋一般现在时」，主语＋will＋动词原形，比如：在这里填写结构说明，比如：

If it rains tomorrow, we will stay at home.

易错点及特别注意：If 从句表示将来时，通常也不用 will。辨析一组句子：

If she comes tomorrow, I will tell her.　（✓）

If she will come tomorrow, I will tell her.　（✗）

定 义

描述与现在事实不符，或将来发生可能性较小的情况。

结 构

通常为「If＋一般过去时」，主语＋would＋动词原形，比如：

1. If I won the lottery, I would travel around the world.

2. If I were you, I would talk to the teacher.

易错点及特别注意：正式表达中，假设语气里的 be 动词常用 were：If I were ... / If he were ...

定 义

描述过去没有发生的事情，并想象如果当时情况不同，结果会怎样。

结 构

通常为「If＋had＋过去分词」，主语＋would have＋过去分词，比如：在这里填写结构说明，比如：

1. If I had studied harder, I would have passed the exam.

（实际情况为：I didn't study harder, so I didn't pass the exam.）

2. If they had left earlier, they would not have missed the train.

易错点及特别注意：过去没有发生，现在已经无法改变。

If you study hard, you will pass the exam.

将来努力，就有可能通过。

If you studied harder, you would pass the exam.

现在不够努力，这是一种假设建议。

If you had studied harder, you would have passed the exam.

过去没有努力，所以考试没有通过。

快速判断：将来真实可能 → 第一条件句｜现在不真实或可能性小 → 第二条件句｜过去没发生、已经无法改变 → 第三条件句

PRACTICE 1Identify the Type · 判断条件句类型

先判断时间和可能性，再选择结构。写出 First、Second 或 Third。

1. If it is sunny tomorrow, we will go cycling. ＿＿＿＿＿

2. If I were taller, I would join the basketball team. ＿＿＿＿＿

3. If she had set an alarm, she would not have been late. ＿＿＿＿＿

4. If you finish your homework, you will be able to watch TV. ＿＿＿＿＿

5. If I knew the answer, I would tell you. ＿＿＿＿＿

6. If they had taken a map, they would not have got lost. ＿＿＿＿＿

PRACTICE 2Choose the Correct Form · 选择正确形式

1. If Tom ＿＿＿＿＿ (study) hard, he will improve his English.

2. If I ＿＿＿＿＿ (be) you, I would apologise to her.

3. If we had left earlier, we ＿＿＿＿＿ (catch) the bus.

4. If it ＿＿＿＿＿ (rain) this afternoon, we will stay indoors.

5. She would travel more if she ＿＿＿＿＿ (have) more free time.

6. If you had told me, I ＿＿＿＿＿ (help) you.

7. If Lucy ＿＿＿＿＿ (come) tomorrow, I will give her the book.

8. What would you do if you ＿＿＿＿＿ (find) a wallet in the street?

Tip: Choose the form that matches the time and possibility: present + will, past + would, or had done + would have done.

PRACTICE 3Complete the Sentence · 根据含义完成句子

1.（将来可能）If I have enough time this weekend, I ＿＿＿＿＿＿＿.

2.（真实条件）If you don't hurry, you ＿＿＿＿＿＿＿.

3.（现在假设）If I could speak three languages, I ＿＿＿＿＿＿＿.

4.（给出建议）If I were you, I ＿＿＿＿＿＿.

5.（过去遗憾）If I had gone to bed earlier, I ＿＿＿＿＿＿＿.

6.（过去相反结果）If they had checked the weather, they ＿＿＿＿＿＿＿.

PRACTICE 4Translation & Output · 翻译与开放输出

1. 如果明天不下雨，我们就去公园。

＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿

2. 如果我是你，我会先和父母谈一谈。＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿

3. 如果我昨天更认真复习，我就会做得更好。＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿

4. 开放表达：What would you do if you had a month-long holiday? 写 2—3 句话。＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿＿