Definition & Examples

“if clauses” are also known as conditional sentences and they are used to talk about possibilities or conditions and their outcomes. There are three types of if clauses:(Normally, we use type 1 if clause.)

Type 1:
If + present simple, future simple (will/won't + base form of verb)

This type is used to talk about a general truth or a possibility in the future.

Examples:
If it rains, the streets will be wet.
If she studies hard, she'll pass the exam.

Type 2:
If + past simple, would/wouldn't + base form of verb

This type is used to talk about a hypothetical situation in the present or future.

Examples:
If I had a million dollars, I would quit my job.
If she saw that, she would be surprised.

Type 3:
If + past perfect, would/wouldn't + have + past participle

This type is used to talk about a hypothetical situation in the past and its consequence.

Examples:
If I had known, I would have gone there.
If she had worked harder, she would have passed the exam.

It is important to note that each type of if clause requires a specific tense in the main clause.

初中-要求掌握if真实条件句(Type 1)

在了解这个 if 从句前，我们需要知道一些基础知识：

所有的从句、复合句、并列句，都遵循一个结构：句子 1 + 连接词 + 句子 2，而 if 在这里就是充当 “连接词” 的作用。

分清楚结构之后，那么我们需要记住以下的结构：主句 + 连接词 if + 从句，而以下的时态原则的表达，就和 “主”、“从” 相关了。

重点来了，记住以下的思维导图 – 四个时态原则：

补充：如果把 if 从句放前面，则只需要加一个逗号即可，e.g.If it doesn’t rain tomorrow, I will go on a picnic.

高中-要求掌握if的非真实条件句，也叫虚拟条件句(Type2&3)

一、虚拟条件句：
条件状语从句是非真实情况，在这种情况下要用虚拟语气。
1．对现在虚拟：条件从句与现在事实不一致，其句型为：
If ＋主语＋过去时(were/did)….，主语＋ should (could, would, 或might) ＋动词原形
(1) If I were you, I would seize the chance.
(2) If I missed the train, I would not arrive on time.
2．对过去虚拟：条件从句与过去事实不一致，其句型为：
If ＋主语＋had＋过去分词….，主语＋ should（could, would, 或might）＋ have ＋过去分词
(3) If you had told me the truth, I wouldn’t have been like an idiot last night.
(4) If I had not studied hard, I wouldn’t have been admitted to my ideal school.
3．对将来虚拟：条件从句与将来事实不一致，其句型为：
If ＋主语＋过去时/ should ＋动词原形/ were to＋动词原形……，主语＋ should (could, would, 或might) ＋动词原形
(5) If it should rain tomorrow, we would cancel our picnic plan.
(6) If I were to be a millionaire one day, I could help those in poor conditions.

练习-Here are some exercises on if clasuses.

Exercise 1:

Fill in the blanks with the correct form of the verb in each sentence:

If it rains tomorrow, I __________ (stay) home.
If he __________ (arrive) on time, we can start the meeting.
If she __________ (have) enough money, she would buy a car.
If I __________ (know) the answer, I would tell you.
If it __________ (not be) so cold, we could go for a walk.

Answers:

will stay
arrives
had
knew
wasn't

Exercise 2:

Convert the following sentences from simple present to present conditional:

I watch TV every night.
She visits her grandparents every weekend.
He reads a book before bed.
They play soccer in the park every Saturday.
We go to the movies once a month.

Answers:

If I watch TV every night.
If she visits her grandparents every weekend.
If he reads a book before bed.
If they play soccer in the park every Saturday.
If we go to the movies once a month.

Exercise 3:

Rewrite the following sentences in the past conditional:

If I have a lot of money, I will buy a new car.
She will be happy if she gets the job.
He will visit his friends if he has time.
If it rains, we will stay at home.
If they finish their work early, they will go to the beach.

Answers:

If I had a lot of money, I would buy a new car.
She would be happy if she got the job.
He would visit his friends if he had time.
If it rained, we would stay at home.
If they finished their work early, they would go to the beach.