关于钒催化剂各组分的作用,下列描述正确的是()。A.五氧化二钒是催化剂的活性主体,起

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问题:

关于钒催化剂各组分的作用,下列描述正确的是()。

A.五氧化二钒是催化剂的活性主体,起主要的催化作用

B.硫酸钾是催化剂的助剂,对催化反应起一定的辅助作用

C.二氧化硅是催化剂活性组分的载体

D.单质钒只能作为原料,不能单独起催化作用

考点:硫酸生产工考试硫酸生产工考试题库
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木马在建立连接时,并非必须的条件是_________。

A.服务端已安装了木马

B.控制端在线

C.服务端在线

D.已获取服务端系统口令

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什么是电气设备短路事故?

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在M2000V2拓扑上,网元右键菜单中的“同步“,是指()。

A.把网元配置数据从网元侧上载到网管侧

B.把网元配置数据从网管侧下载到网元侧

C.以上都不对

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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.

To keep track of a disease such as influenza, WHO must have ______.

A.highly trained experts

B.cooperation from every doctor

C.good reporting services

D.time to study the facts

题型:多项选择题

()是建设工程管理的核心。

A.业主方项目管理

B.工程总承包方项目管理

C.施工方项目管理

D.设计方项目管理

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