在受精后的第（）后，胎儿的基本结构与新生儿相似。

A.8周

B.16周

C.24周

D.32周

根据括号中的要求改写句子。

1. I  heard of the news that the boy was lost.(改为同义句) 

   I______the news that the boy was lost.

2. You should take care of your little sister.(改为同义句)

    You should______your little sister.

3. Our school is not the same as your school.(改为同义句)

    Our school is______your school.

4. I think English is not easy to learn.(改为同义句)

    I think English is______to learn.