题干

静脉的作用是收集血液返回心脏,下列静脉的特点中与防止血液倒流相适应的结构特点主要是(   )

A:与心脏相通

B:管壁薄而弹性小

C:管腔大,其内表面有静脉瓣

D:与动脉伴行

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答案(点此获取答案解析)

C

同类题4

Choose the best answer to complete the passage.

    In our country we think being modest(谦虚的) is a virtue(美德) and being proud is a bad thing. One day, I heard an American boy say to a Chinese student, “You speak very good English.” But the girl answered, “No, no. My English is very poor.” The foreigner was quite 1 at the answer. Thinking he had not made himself understood or the girl had not heard him 2. He said, “Yes, indeed, you speak very well.” 3 the girl still kept saying, “No.” In the end the American boy could not understand and didn't know 4 to say.

    What's wrong with the girl's answer? She didn't 5 a compliment(恭维) in the same way as the American people do. She should answer “Thank you” instead of “No”. She 6 understood what the American boy had said, but she thought she should be modest. In the 7, people will feel 8 and confident when they are praised. So if someone says the 9 you have cooked are very delicious, you should say, “Thank you”.

    If you are modest and say, “No, I'm 10 I can't do it well”, while working in a western country, people may think that you really can not do it. If you often say, “No”, you'll certainly be looked down upon by 11. When asking 12 a job, if one says something like, “Yes, I can certainly do it” instead of “Let me have a try”, he or she will 13 get it. So in the west, you should be brave to show your self-confidence. In my opinion, being confident does not 14 being proud, so sometimes you should be confident 15 being modest.