同义句转换。

1.We should help our parents do the housework at home.

   We should help our parents __________  __________ at home.

2. My classmate lent me a dictionary two weeks ago.

   I __________ a dictionary __________ my classmate two weeks ago.

3. Don’t forget to tell Jim .

   __________  __________ tell Jim.

4. Why not ask the policeman to help you ?

   Why __________  __________ask the policeman __________ help you?

5. Don’t worry. I can look after your dog well.

   Don’t worry. I can __________  __________  __________  __________ your dog.

RNA是联系DNA和蛋白质的纽带，在机体里面RNA的种类有三种，mRNA、tRNA、rRNA，它们在蛋白质的合成过程中都发挥重要的作用。

下列关于mRNA的描述哪个正确

A．指导碱基合成
B．修复损伤的DNA C．蛋白合成过程中的模板
D．核糖体的组成部分
E．携带氨基酸并与密码子结合