用所给词的适当形式填空。

1. His sister is a good ________ (dance).

2. Please pass ________ (I) some salt.

3. He is ________ (run) in the playground.

4. It's important to be ________ (health).

5. I like eating ________ (dry) fish very much.

6. My father ________ (mend) a clock now.

7. Some boys ________ (lie) on the beach(海滩).

8. I _______ (chat) with my friend on the Internet now.

9. My father often ________ (watch) TV after supper.

10. ________ (not open) the door. It's too cold outside.

基因D、d和T、t是位于两对同源染色体上的等位基因，在不同情况下，下列叙述符合因果关系的是（）

A.进行独立遗传的DDTT和ddtt杂交，则F2双显性性状且能稳定遗传的个体占1/16

B.后代的表现型数量比为1：1：1：1，则两个亲本的基因型一定为DdTt和ddtt

C.基因型为DDtt的桃树枝条嫁接到基因型为ddTT的植株上，自花传粉后，所结果实的基因型为DdTt

D.基因型为ddTt的个体，如果产生的配子中有dd的类型，则一定是在减数第二次分裂过程中发生了染色体变异