Conditional sentences express a choice and the possible consequences of that choice.
There are three types of conditional sentences: Real, Unreal and Unreal Past. The first
type is the easiest to learn. It involves a present choice and a future consequence.
If you drive north for three miles, you will get to Columbus.
If he doesn't exercise, Fred will gain weight.
If you purchase a raffle ticket, you might win a car.
Real conditional sentences contain two parts, the if clause, and the result clause.
The if clause indicates the choice and is expressed in present tense. It indicates a choice and can be either positive or negative. If statements can also imply the opposite choice and result.
|If you study hard you will pass the
||(Choice and possible result)
|If you don't study hard, you could fail.
||(Implied opposite choice and result.
The result clause indicates the consequence or possible consequence, and
is expressed in future tense or with modals can, could or might.
|If you eat your spinach,
||you will grow stronger.
|If I quit my job,
||I can spend more time with the kids.
|If Troy moves to Hollywood,
||he might become a movie star.
Textbook Recommendation : Touchy Situations, Chapter 11
See also :
Conditional Introduction (from Englishpage.com)