用所给词的适当形式填空。 1. Oh, it's seven o'clock. It's time______ (go) to school. 2. The box is too heavy. Let me ______ (help) you. 3. Lily _____ (have) some picture books. 4. Listen! Who ______ (sing) in the room? 5. There ______ (be) a boy and some girls over there. 6. Sometimes he _______ (watch) TV in the evening. 7. The two boys are _______ (China). 8. Tom, with his friends, _________ (be) playing football over there. 9. There are five ______ (sheep) under the tree. 10. There are many _____ (cloud) in the sky.