Introduction
- If you haven't got television, you can't watch it.
- If you go to one of the agencies, they have a lot of temporary jobs.
- If someone else has requested the book, you would have to give it back.
- If you lived on the planet Mercury, you would have four birthdays in a single Earth year.
In open conditions we use the present to refer to the future (if you go to one of the agencies). When we talk about something unreal we often use the past (if you lived) and would (you would have four birthdays).
NOTE
When the condition is true, we use verb forms in the normal way.
- Well, if your friends left half an hour ago, they aren't going to get to Cornwall by tea time.
The if-clause usually comes before the main clause, but it can come after it.
- We lose our money if the company fails.
Type 0 conditionals
a. The pattern is if...+ present... + present.
- If the doorbell rings, the dog barks.
- If you heat iron, it expands.
Here the pattern means that one thing always follows automatically from another.
We can use when instead of if.
- If/When I reverse the car, it makes a funny noise.
( = Every time I reverse the car,...)
b. We can also use Type 0 for the automatic result of a possible future action.
- If the team win tomorrow, they get promotion to a higher league.
This is an open condition. It leaves open the question of whether the team will win or not.
NOTE
As well as the present simple, we can use the continuous.
- If you're practising on the drums, I'm going out.
Source: John Eastwood, Oxford Guide To English Grammar.
