Нужно вставить if/while/unless/as/as soon as.
1.You won't pass the Math exam ...
you start getting ready to it right now.
2.You'd better stay at home ...
you feel sick.
3.Jane prefers to do her homework ...
she gets back from school.
4.It's raining outside. Don't go out ...
you take your umbrella.
5.Call me ...
you get to the place.

you feel tired, go to bed right now.
6.We can stay at home ...
you want to go out somewhere.