用所给动词的适当形式填空。
1. — I _____ (buy)a beautiful pen.
— When _____ you ____ (buy) it?
2. He _____ (not post) the letter for me. It is still on his desk.
3. While the Reads _____ (have) supper,the bell rang.
4. He _____ (fall) off the bike last week, so he _____ (feel) terrible.
5. He _____ (ride) his bike this time yesterday.
6. He _____ (look for) his lost brother these years.
7. — What have you done with the apples?
— We have just _____ (eat) them.
8. Our teacher said that air _____ (keep) moving all the time.
9. — Who _____ (knock) at the door?
— It's me.
10. Look! The snow _____ (stop). Let's go and make a snowman.
