依次填入下列横线处的词语，最恰当的一组是 (    )

①专家们________指导小股民要耐得住寂寞，别人恐惧时你要贪婪，别人贪婪时你要恐惧。

②除非身体有问题，________年轻人不给老人让座，道理上总说不过去。

③互联网已经延伸到每家每户和田间地头，________互联网的优势还没有完全地发挥，________具有想象不到的开发空间。

   Hello, boys and girls. My name is Kangkang. I’m from Tianjin. I’m No.1 middle school.
   My mother works in No.1 middle school. She teaches Chinese. My father is a doctor in a hospital. They both work hard.
   On Sunday my mother and I often do some shopping. My mother likes shopping a lot. We will go shopping this Sunday afternoon. My mother says she will buy me a red coat. But I don’t like red. I want a yellow one. My mother says yes to me. I am happy.
   My father doesn’t like shopping at all. He likes animals best. He often takes me to the zoo. My favorite animal is the panda. I think panda are very cute. This Sunday morning my father will go to the zoo with me.
   I love my parents very much. They love me, too. I have a happy family.

根据生物的结构与功能很难造出机器。 （  ）

求下面圆的周长．