Real and Unreal

complex sentence structure using "if"

If it is cold outside, you should wear a jacket. When it is cold outside, I wear a jacket.

If I have the the money, i am going to marry her.

when the result is surprising

Can use either simple/progressive in "if" clause

WISHFUL THINKING

PRESENT

If I had money, I would buy a boat.

PAST

If I had known, I would have stayed home.