题干

按照达尔文的进化论观点,长颈鹿的颈很长,其原因是(  )

A:变异朝着有利于生殖的方向发展的结果

B:代代经常使用颈脖子(吃高处叶子)的结果

C:繁殖后代的需要

D:颈短的个体被淘汰,颈长的个体被保留,是自然选择的结果

上一题 下一题 0.0难度 选择题 更新时间:2014-06-06 09:17:12

答案(点此获取答案解析)

D

同类题2

阅读下列短文,从每题所给的四个选项(A、B、C和D)中,选出最佳选项。

    It was a bad time for me. I was low emotionally and tired physically. Probably because of this I hadn't shaved for a few days. Also, because I had been doing some repairs at my daughter's house, I was dressed quite scruffily(不整洁地). Boarding the bus to go home I saw it was almost full so I found a rail(扶手) to lean against.

    That's when a young woman, sitting with her child, stood up and offered me her seat. ‘Wow!' I thought. Out loud I said, “Do I look that old and tired?” She replied, “You look like you've had a tough day.” I thanked her sincerely and stayed standing.

    A moment later a man rose from his seat at the back of the bus and made his way towards me, walking past several people on the way. Then he told me about his addiction(毒瘾) problems, asked my advice, and just chatted about life for a few minutes. Then he went back to his seat. Very random!

    Watching him go, I also looked at the bus-load of people between me and his seat. He hadn't chosen to talk to those strangers. He chose to talk to this stranger, for whatever it meant to him and whatever comfort it brought him. Why?

    That's when it occurred to me. I must have looked like I had been where he was. I probably looked like a man who would understand a difficult life. I was humbled(谦卑的) and encouraged at the same time by the realization that even when we are at our lowest we can still help others — if we look like we might be able to meet them where they live or walk a while in their world.