填空题：用人单位承担社会保险费的义务，是（）的主要缴纳者。

题型：选择题

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题型：单项选择题

①因为细胞这种旺盛的生长过程如不加抑制地发展下去，细胞病变生成肿瘤的可能性极大 ②当人体处于生长发育期时，体内细胞生长迅速 ③但是，衰老程序一旦启动就不可逆转 ④但这一细胞迅速生长的过程同时也给人体带来了危险 ⑤这一在人类年轻时启动的保护程序，最终发展成了人类的死亡程序 ⑥为了避免这种危险，人体就会启动衰老程序。通过一些功能基因降低细胞增殖能力排列组合最连贯的是( )。

A．⑤②①⑥③④

B．②④①⑥③⑤

C．②⑥①④③⑤

D．⑤⑥②③①④

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题型：多项选择题

类风湿性关节炎的关节表现特点()

A．夜间僵硬

B．四肢小关节受累

C．形如梭状指

D．仅肿胀不疼痛

E．最终关节畸形

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题型：判断题

人体的血液循环可以分为肺循环与体循环两部分，这两部分血液循环不是同时进行的。

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题型：单项选择题

In 1957 a doctor in Singapore noticed that hospitals were treating an unusual number of influenza-like cases. Influenza is sometimes called "flu" or a "bad cold". He took samples from the throats of patients in his hospital and was able to find the virus of this influenza.
There are three main types of the influenza virus. The most important of these are type A and B, each of them having several subgroups. With the instruments at the hospital, the doctor recognized that the outbreak was due to a virus in group A, but he did not know the subgroup. Then he reported the outbreak to the World Health Organization in Geneva. WHO published the important news alongside reports of a similar outbreak in Hong Kong, where about 15-20 percent of the population had become ill.
As soon as the London doctors received the package of throat samples, doctors began the standard tests. They found that by reproducing itself with very high speed, the virus had grown more than a million times within two days. Continuing their careful tests, the doctors checked the effect of drugs against all the known subgroups of virus type A. None of them have any protection. This, then, was something new, a new influenza virus, against which the people of the world had no help whatever.
Having found the virus they were working with, the two doctors now dropped it into the noses of some specially selected animals, which get influenza much as human beings do. In a short time the usual signs of the disease appeared. These experiments proved that the new virus was easy to catch, but that it was not a killer. Scientists, like the general public, call it simply Asian flu.
The first discovery of the virus, however, was made in China before the disease had appeared in other countries. Various reports showed that the influenza outbreak started in China, probably in February 1957. By the middle March it had spread all over China. The virus was found by Chinese doctors early in March. But China is not a member of the WHO and therefore does not report outbreaks of disease to it. Not until two months later, when travelers carded the virus into Hong Kong, from where it spread to Singapore, did the news of the outbreak reach the rest of the world. By this time it was well on its way around the world.

The type of influenza discussed in this story ______.

A．had been classified years before

B．could not be cured by any known drug

C．could be prevented from spreading

D．could not affect adults

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用人单位承担社会保险费的义务，是（）的主要缴纳者。

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