Conditional sentences consist of an if-clause and a main clause. There are four main types of conditional sentences:
|use and example
|for general truths and laws of nature
If you mix red and white, you get pink. (this is always true)
|will + infinitive
|for real possible situations in the present or future
If you call me tonight, we will go out.(this is possible)
|would + infinitive
|for unreal, imaginary situations in the present or future
If I had more free time, I would go on a holiday.(but I do not have and I won’t go)
|would have +past participle
|for unreal, imaginary situations in the past
If I had studied harder, I would have passed the exam.(but I didn’t study and I didn’t pass)
In 0 and 1 type conditional sentences we can use when instead of if.
If you ask Anna, she will come with you.
When you ask Anna, she will come with you.
unless = if not
If the if -clause in 0 or 1 type contains a negative verb, we can substitute if with unless (followed by a positive verb).
If we don’t hurry, we will miss the bus.
Unless we hurry, we will miss the bus.
There can be different types of mixed conditionals as well.
Try the quiz here.