Situation under your condition
Real
Unreal
It is/was permanent and true all the time.
It can happen in the future/
If Present Simple, Present Simple
If your car is old, it probably needs a road test
If Past Simple, Past Simple
If she made a new dish, she tried it out on friends straight away.
If Present Simple, Future Simple
If we don’t water those plants, they will die.
in the present (now)
in the past (then)
If-clause: Past Simple
If we were rich
, would + infinitive
, we would buy a house in the Caribbean.
If-clause: Past Perfect
, would have + 3rd form
If you had opened the door
, she would have gone again.