If it (rain) ......... tomorrow, we (not go) ......... swimming.
If it rains tomorrow, we won't go swimming.
If people (park) ... in the wrong place, they (have) ... to pay a fine.
If people park in the wrong place, they have to pay a fine.
If I (not feel) ... well tomorrow, I won't go to school.
If I don't feel well tomorrow, I won't go to school.