用所给动词的正确形式填空。
1. We know the earth _____ (travel) around the sun.
2. Can you see the students _____ (plant) trees on the hill now?
3. —Where's your father?
—He _____ (clean) the car behind the house.
4. I am sure she _____ (be) a very good teacher in a few years.
5. He wanted my help. So I stopped _____ (help) him.
6. Was Jane very busy _____ (plan) a boat trip with you last night?
7. It is very important _____ (not give) your goldfish too much food.
8. The boss usually makes his workers _____ (work) for twelve hours every day.
9. David _____ (fall) off the tree and hurt his legs a moment ago.
10. Millie, _____ (not frighten) the dog, or it will bark at you.