What Will Happen?
Zero Conditional
Use the zero conditional if an action always occurs as the result of another action. The zero conditional is used to express conditions that are always true.
Example:
Tom reviews the inventory listing before he starts the meeting.
If the production overheads are too large, the company always slows production.
The present simple is used in both the 'if' clause and the result clause.
'If' clause - present simple + , + result clause - present simple
Tom reviews the inventory listing before he starts the meeting.
If the production overheads are too large, the company always slows production.
Do not use a comma, when placing the result clause first.
Tom reviews the inventory listing before he starts the meeting.
First Conditional
Use the first, or 'real', conditional if an action will occur if something happens. The first conditional is used when a result is realistically possible.
'If' clause - present simple + , + result clause - future with will
If they hire the designer from New York, they will pay twice as much.
I might quit using this privately owned social networking site if an open source version is made available.
Do not use a comma, when placing the result clause first.
She will join the union if Jack Reed tells her to join.
'Unless' is also used in the first conditional to mean 'if not'.
If he doesn't come soon, we won't go to lunch = Unless he comes, we won't go to lunch.
Use of 'May' and 'Might' in the First Conditional
When a future result is not certain based on a condition, use 'may' or 'might'.
'If' clause - present simple + , + result clause - 'may / might' + verb
We'll switch to a direct ship model if we find an online retailer who can provide us with buyers.
He might take it to the people in human resources if the problem persists.