If you don't study, you (pass) the exam and then you'll have to retake the semester.
If you don't study, you WON'T the exam and then you'll have to retake the semester.
If you boil water, it (evaporate).
If you boil water, it EVAPORATES.
If I'm sick tomorrow, I (stay) home.
If I'm sick tomorrow, I 'LL STAY home.
I (call) you if I have any questions.
I WILL CALL you if I have any questions.
If I eat too much, I always (feel) bad.
If I eat too much, I always FEEL bad.
I always (take) medicine if I'm sick.
I always TAKE medicine if I'm sick.
You never (sleep) well at night if you drink too much coffee.
You never SLEEP well at night if you drink too much coffee.