Conditional Sentences
“if-clauses”
Conditional Sentences
We use conditional sentences to talk about a situation or an action and its result. The basic idea of a conditional sentence is that if something happens, then something else happens.
A conditional sentence consists of two parts:
An if-clause (situation / action)
A main clause (condition / result)
Types of conditional sentences
There are totally 4 types of conditional sentences which have different meanings and structures.
Type 0
Type 1
Type 2
Type 3
0 conditional
We use this conditional to express general truths.

1st conditional
We use the 1st conditional to talk about possible situation in the future.
We also use this conditional to express persuasion, warning and threat.

Persuasion: 勸說
I’ll take the children to the party if you collect them from school.
Warning: 警告
If you try to take the short cut, you’ll get lost.

Threat: 恐嚇
If you poke your brother again, I’ll thrash you.
Other variants
If + present, imperative 命令句





 No subject in the main clause.







We can also use should in the if clause of Type 1 conditional.

If you should have any questions, please don’t hesitate to talk to me.

Inversion: 倒裝句式
Should you have any questions, please don’t hesitate to talk to me.
2nd conditional
Unreal
Hypothetical
Talking about something that is impossible or contrary to fact.
We often use were in place of was to talk about something contrary to fact.
Compare the following two sentences:
If it gets colder tonight, I will turn on the heating.

If it got colder tonight, I would turn on the heating.
Type 1 : a real possibility
Type 2 : viewed as not a real possibility
Other variants
Should
I shouldn’t get to sleep at all if I lived next to that noise.

Were + infinitive
If you were to have a few minutes free, I ‘d really appreciate to have a coffee with you.
Inversion: were + subject
When we use were in the if clause, we can invert were and the subject of the clause, and leave out if altogether:

Were he really ill, I might feel more sympathetic.
3rd conditional
We use this conditional to speculate (推測) about past events, and about how things that happened or didn’t happen might have affected other things.
We also use this to express regret 後悔 and reproach 責備.
Other variants
Inversion: had + subject + past participle

Had I known he was ill, I would never have shouted at him.
Using supposing, as long as, unless

We can use supposing and as long as to talk about an act of imagination.

Where will you go supposing you manage to have a holiday?
I would help him as long as he asked me nicely.

 Type 1 and 2
Unless
We use unless to express a stronger degree of reservation 異議.

I won’t come round unless you phone.
I wish
We can also use I wish to refer to hypothetical events.

Present:
I wish she paid a little more attention.

Past:
I wish I hadn’t agreed to take part in the speech.