将这些句子改为祈使句　急急急急急

将这些句子改为祈使句　急急急急急
1.you should be careful when you ride a bike on the street
2.we must cross the street only when we see the green "walk"sign.
3.we must keep quiet in class
4.we should not drive too fast .
5.we must not make a wrong turn .
6.we must not park in the wrong place.