防止混凝土早期冻害的措施包括（）。A.提高混凝土早期强度 B.掺用缓凝剂 C.掺用引

抗剪试验中，固结时间的控制是试验是否成功的主要影响因素之一，对一般粘性土，当垂直测微表读数不超过（）时，即认可达到压缩稳定。

A.0.01mm/h

B.0.1mm/h

C.0.005mm/h

D.0.05mm/h

下列各句中，没有语病的一句是

A．该厂先后被评为市先进企业和二轻局文明单位，市政府连续五年授予该厂“重合同，守信誉”单位。

B．我们要为勇于创新的人创造宽松环境，提供有利条件，不要动不动就给他们戴紧箍咒。

C．我们要善于寻找并最后判断诗人提供的形象背后所蕴含的情感，欣赏活动不可停留在表面意思的掌握上。

D．强调联合制作的大戏，让人们不仅看到了中国戏曲的整体进步，而且看到了中国戏曲在现代化问题上迈出的可喜一步。

应当先履行合同债务的当事人，可以中止履行不安抗辩权的情形是：有确切证据证明对方( )。

A．经营状况恶化
B．丧失商业信誉
C．转移财产
D．更换法定代表人

公安机关在行使紧急优先权时，对于造成的损失没有任何赔偿义务。 ( )

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 types A and B, each of them having several sub-groups. With the instruments at the hospital the doctor recognized that the outbreak was due to a virus group A, but he did not know the sub-group. He reported the outbreak to the World Health Organization in Geneva. W. H.O. published the important news alongside reports of a similar outbreak in Hong Kong, where about 15%—20% of the population had become ill.

As soon as the London doctors received the package of throat samples, they began the standard tests. They found that by reproducing itself at very high speed, the virus had multiplied more than a million times within two days. Continuing their careful tests, the doctors checked the effect of drugs used against all the known sub-groups of virus type A. None of them gave any protection. This then, was something new: a new influenza virus against which the people of the world had no ready help whatsoever. Having isolated the virus they were working with, the two doctors now dropped it into the noses of some specially selected animals, which contact influenza in the same way as human beings do. In a short time the usual signs of the disease appeared. These experiments revealed that the new virus spread easily, but that it was not a killer. Scientists, like the general public, called 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 of 1957. By the middle of March it had spread all over China. The virus was found by Chinese doctors early in March. But China was not a member of the World Health Organization and therefore did not report outbreaks of disease to it. Not until two months later, when travelers carried 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 started on its way around the world.

Thereafter, WHO’s Weekly Reports described the steady spread of this virus outbreak, which within four months swept through every continent.

London doctors considered（）

A. “Asian” flu as a bad cold

B. there were three main types of influenza virus

C. it was necessary to test the other virus groups besides group

D. the influenza called “Asian” flu a new one