The cigarette end thrown away by a careless farmer ______ the big fire and caused a great loss to them．

Would you like to go out to play football with me— ______ But I should do my homework first.

If you want to be healthier, you shouldn’t do _____ inthe classroom all the time but domore _____ on the playground.

We can’t have some students ______ cheating in the exam.

Kitty and Simon will arrive___________Shanghai with their parents this week .