1. You will hurt your teeth if you (eat) too much candy.
2. Do not watch the horror film if you (get) scared easily.
3. If there (be) fewer trees, there (be) more pollution.
4. If our flight is on time, we (arrive) in Beijing at 10 a.m.
5. What will you buy if you (have) a lot of money?
6. If she gets up late, she (not catch) the early bus.
7. Unless it (rain), we are going on a picnic this Saturday.
8. I (not lend) the book to you unless you return it to me on time.
9. I won't go unless he (come) to invite me himself.
10. —Can we play football in the playground, Mr Li?
—No, unless you (finish) your homework first.
11. We will be late unless we (leave) now.
12. The little boy (not stop) crying unless you give him what he wants.

二、根据要求改写下列句子
1. You cannot speak English. It's hard to travel in England. (用if连接两个句子)
2. Millie gets home late. Millie will miss her favourite TV programme. (用if 连接两个句子)
3. will, if, a, you, football, like, are, you, this, fan, game (.) (连词成句)
4. If you practise hard, you will improve your skills. (用unless改写为同义句)
5. Don't touch the instruments unless the teacher allows you to. (用if ... not改写为同义句)
6. Mary can't see clearly if she doesn't wear glasses. (用unless改写为同义句)