问题
单项选择题
随胆汁排出的药物或代谢、在肠道运转期间重洗收而返回门静脉的现象是（）。
A.零级代谢
B.首过效应
C.肠肝循环
D.肾小管重吸收
E.被动扩散
答案
参考答案：C
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随胆汁排出的药物或代谢、在肠道运转期间重洗收而返回门静脉的现象是（）。
A.零级代谢
B.首过效应
C.肠肝循环
D.肾小管重吸收
E.被动扩散
参考答案：C
| 完形填空。 | |||
| The population problem may be the __1__ one of the world today. The world's population is growing __2__ . Two thousand years ago, there were only 250 million people __3__ the earth. Four hundred years ago, the number was __4__ 500 million. But at the beginning of the __5__ century, the world's population was about l, 700 million. In 1970, this number was 3,600 million. In 1990, the number was five billion. A __6__ report says that the world population will __7__ six billion by the end of the 20th century. This is just ten __8__ after it __9__ five billion. People say that by the year 2010, __10__ may be seven billion. | |||
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