题干

下图为人体内某结构的血流情况模式图,B代表某器官或结构,A,C代表血管,箭头代表血流方向,下列叙述正确的是

A:若B为肺,则A中流动脉血,C中流静脉血

B:若A,C都流动脉血,则B代表的一定是肾小球

C:若A为上腔静脉,C为肺动脉,则B中有防止血液倒流的瓣膜

D:若B为小肠,则C中的氧气含量增加,二氧化碳含量减少

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答案(点此获取答案解析)

C

同类题2

阅读下而短文,在空白处填入1个适当的单词或括号内单词的正确形式。

    I'm Yuan Longping. Look at my sunburnt face and arms and my slim strong body and you will think I'm ____ like a farmer than a scientist. In fact I ____(struggle) for the past five decades to help ____(farmer). In 1974, I began to grow a so-called super hybrid rice. This special strain of rice makes ____ possible to produce one-third more of the crop in the same fields.

    I was born into a poor farmer's family in 1931. When I was young, I saw many people go hungry often. So I have devoted myself to ____(find) ways to increasing rice harvest without expanding the area of fields since I graduated from Southwest Agriculture College in 1953. Now more than 60% of the rice____(produce) in China each year is from this hybrid strain. I am circulating this knowledge in India, Vietnam and other less developed countries to increase their harvest. Perhaps you think I am rich. ____(actual) I live a simple life. I care little for money. In my opinion, a person with too much money will have more troubles. I don't want to be famous ____ I prefer to have more time to do my research. In my free time I love listening to music, playing mah-jong and reading. I once had a dream, in ____ I saw rice plants as tall as sorghum and each ear of rice was as big as an ear of corn and each grain of rice was as huge as a peanut. Now I have another dream-to export my rice so that it can ____(grow) all over the world.