用所给单词的正确形式填空。

1. Let's ____________ (stop) the car.

2. Don't ____________ (worry). I can help you.

3. I can find it ____________ (easy).

4. How many ____________ (knife) do you have? What do the man' s parents want him to be? A．A teacher．B．An engineer．      C．A doctor．

5. ____________ (not do) your home work now.

6. He ____________ (show) me his photo now.

7. The boat ____________ (cross) the river a moment ago.