题目：
用所给词的适当形式填空。
1. _____ ( eight, year, old) should be allowed to drive.
2. Anna wants to get her ears_____ ( pierce).
3. Young trees should _____( water) as often as possible.
4. You need ______ (wear) warm clothes, or you'll catch a cold.
5. The old should __ (speak) to politely.
答案：
1. Eight-year-olds 2. pierced 3. be watered 4. to wear 5. be spoken
