3. Scientists can even _________(combine) a plant and an animal.

2. Sam doesn’t want _________ (clone).

1. Let’s _________ (sing) this song together.

10. Could you tell me what the ________(different) is between a horse and a mule?

II. 用所给单词的适当形式填空

9. The machine is a great _______(helpful) in making cakes.

8. I think oranges are _______(juice) than bananas.

7. What fruit do you like ________(well)?

6. Which do you like ________(well), a cat or a dog?

5. Lily and Lucy are t_______. They were born of the same mother at the same time.

B. 用所给单词的适当形式填空

4. We call identical twins c________.