Real in the Present - It happens regularly or sometimes.
More often:
When...simple present..., ...simple present...
               or
...simple present...when...simple present...

Less often:
If...simple present..., ...simple present...
               or
...simple present...if...simple present...		 When I take my grandmother shopping, I always remind her to bring a list.
I get very frustrated when she forgets her list.
When I go to someone's house for dinner, I usually bring some wine.
When I take a vacation, I often take my family to the lake.

If he makes a fuss, I give him a treat.

Real in the Past - It used to happen regularly or sometimes.
More often:
When...simple past..., ...simple past...
               or
...simple past...when...simple past...

Less often:
If...simple past..., ...simple past...
               or
...simple past...if...simple past...		 When I took my grandmother shopping, I always reminded her to bring a list.
I got very frustrated when she forgot her list.
When she went to someone's house for dinner, she usually brought some wine.
When he took a vacation, he often took his family to the lake.

If he made a fuss, I gave him a treat.

Real in the Future - It will happen if/when something else is true.
More possible:
When...simple present..., ...simple future...
               or
...simple future...when...simple present...

Possible:
If...simple present..., ...simple future...
               or
...simple future...if...simple present...		 When I receive permission from your parents, I will forward this to the superintendent.
I will submit her grade when she hands in the final essay.


If the test comes back negative, we won't have to look at anything else.

Unreal in the Present - It would happen only if something else were true.
If...simple past..., ...would simple present...
               or
...would simple present...if...simple past...

Special case:
...would simple present...if...were...		 If she had enough money, Marcy would take summer classes.
I would retire early if I won the Powerball lottery.


I would buy this car if it were less expensive. (not was)

Unreal in the Past - It would have happened only if something else had been true.
If...past perfect..., ...would...present perfect...
               or
...would...present perfect...if...past perfect...

Do not use when.		 If she had had enough money, Marcy would have taken summer classes.
I would have retired early if I had won the Powerball lottery.
She would have bought that car if it had been less expensive.