单项选择题

5-FU的抗肿瘤作用
A、阻断脱氧尿苷酸甲基化为脱氧胸苷酸
B、阻断肌苷酸转变为鸟苷酸
C、阻断胞苷酸转变为脱氢胞苷酸
D、阻断叶酸转变为四氢叶酸
E、阻断肌苷酸转变为腺苷酸

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单项选择题

Which of the following acts is an act of unfair competition stipulated by the law?

A．A municipal government issued a document stipulating that all units must use the water pipes produced by the municipal water company uniformly
B．A department store puts up posters to promote the sales with prizes at the end of the year. The highest prize is a car worth 100,000 yuan
C．A fruit company in a certain city buys a large quantity of fruit and decides to sell it below the cost price because the market is not prosperous and they are going to rot
D．In order to improve the market share of the company's products, company A publicizes its own products with greater consumption advantages to customers by improving technology

单项选择题

Thecore module of manned spacecraft is ____.

A．The experiment module
B．The orbital module
C．The re-entry module
D．The service module