加强网络安全性的最重要的基础措施是______。A．设计有效的网络安全策略 B．选择

二度Ⅱ型窦房传导阻滞的心电图表现是（）

A.长间歇有规则的出现

B.P-P间距逐渐缩短，但无脱漏

C.长间歇后出现房性、交界性或室性逸搏

D.心室律规则

E.在一段长间歇中无P-QP，S-T，间歇常等于正常窦性P-P间距的2倍或3倍

在判断AV型斜视时，需检查眼球向上、下各转多少度时的斜视角()

A．20°

B．30°

C．25°

D．15°

E．10°

On April 24^th, another natural disaster—the oil spill(泄露) in the Gulf of Mexico, happened. Millions of dollars have been used to help stop the spill and to clean up the animals, beaches, and land spoiled by the oil．Unfortunately, when many of these chemicals are used, more damage is caused to the environment, especially to lives in the sea．

But governments seem to accept the risk of transporting millions of tons of oil by ship every day so that we can fill up our cars and drive around and cause even more environmental damage．Interestingly, the biggest companies in the world produce cars, and the next biggest supply the gasoline to make them run.

Of all of today’s environmental disasters, an oil spill may actually be one of the least serious．Although oil is poisonous, it is a natural material．In the end, it breaks down naturally．In 1967 the tanker Torrey Canyon sank off the Scilly Isles near the coast of England and spilled 120,000 tones of oil into the ocean．If you go there today, you will find it hard to see any sign that it ever happened．      

However, we should be thinking more about reducing our dependency on oil．Governments should be encouraging research into new technologies, such as cars run by solar power（太阳能）, electricity, hydrogen, and so on．Much of this research, in the past, was stopped by the oil, gas, and coal．

If the world’s millions of cars were 10% more efficient（高效的）,we would need many fewer tankers crossing the oceans each year．If this happened, the risks of oil spills would be reduced, and the air we breathe would be cleaner and fresher, too．

小题1:What is the passage mainly talking about?

A．Oil spills pollution．

B．What oil pollution is．

C．Oil tanker accidents.

D．How to reduce oil pollution.小题2:How does the author support the idea that oil spills are not as serious as people believe?

A．By giving a description．

B．By making an argument．

C．By giving an example．

D．By drawing a diagram(图表)．小题3:What does the underlined word "risk" in Paragraph 2 refer to?

A．Transportation depending more on oil．

B．Poisonous oil breaking down naturally．

C．Millions of tons of oil spilling into the sea．

D．More environmental damage being caused．小题4:Which suggestion is made for reducing oil tank accidents according to the passage?

A．We should build safer tankers in the near future．

B．We should develop new technologies to cut oil use．

C．Tankers should not be allowed to sail near the coastlines．

D．Countries should build more oil pipelines under the sea．小题5:Where can you read this article?

A．In a story book．

B．In a science magazine．

C．In a novel.

D．In a brochure．

钙和磷的典型缺乏症有（）、（）、（）。

在轴和孔间隙配合，轴的公差带和孔的公差带相互交叠，这种配合称之为( )。

A．过渡配合
B．间隙配合
C．过盈配合
D．任意配合