题干

某药厂欲测试所生产的综合维生素是否会对人体造成不良的副作用,于是征求到了2000名受测者(男性900名,女性1100名),每人每日服用一颗该药厂所生产的综合维生素,六个月后,药厂派出医务人员对全体受测者进行副作用调查。以下哪一项为上述测试过程的最主要缺点                                                                 

A:受测人数太少

B:六个月时间太短

C:缺少对照组(控制组)

D:不同性别的受测人数应该完全相等

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答案(点此获取答案解析)

C

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阅读下面材料, 从每题所给的A, B, C, D四个选项中选出最佳选项。

C

    Life is full of surprises and you never know how things will turn out. Sir John Gurdon. Is a good example of this. As a boy, he was told he was hopeless at science and finished bottom of his class. Now, aged 79, the very same Gurdon shared the 2012 Nobel Prize in Medicine with Japanese stem cell (干细胞) researcher Shinya Yamanaka.

    Like so many scientists, Gurdon shows us where the power of curiosity and perseverance (坚持) can lead.

    At the age of 15 in 1948, Gurdon ranked last out of the 250 boys at his high school in biology and every other science subject. Gurdon's high school science teacher even said that his dream of becoming a scientist was quite "ridiculous".

    In spite of his teacher's criticisms, Gurdon followed his curiosity and kept working hard. He went to the laboratory earlier and left later than anyone else. He experienced thousands of failures.

    "I believe that we will, in the end, understand everything about how cells actually work." Gurdon said.

    In 1962, Gurdon took a sell from an adult frog and moved its genetic (基因的) information i nto an egg cell. The egg cell then grown into a clone of the adult frog. This technique later helped to create Dolly the sheep in 1996, the first cloned mammal in the world.

    In 2006, Gurdon's work was developed by Yamanaka to show that a sample (样本) of a person's skin can be used to create stem cells. Using the technique, doctors can repair a patient's heart after a heart attack.

    "Luck prefers the prepared mind." Gurdon told the Nobel Prize organization. "Ninety percent of the time things don't work, but when they do, you have to catch the chance."