1. If i were you, i would not drive that car until they've repaired it for us.
->If i were you, i would not drive that car...................................................(had)
2.She didn't want to get sunburnt, so she stayed in the shade
->She stayed in the shade..................................................................(avoid)
3. I want you to try really hard to pass this exam
-> I want you to...................................................(effort)
4. You can't go skydiving until you're 18 years old
-> People under...........................................................(allowed)