由于（）和镗杆孔的配合及定位精度要求较高，故能获得良好的镗孔精度，但其制造工艺复杂，

In earliest times, men considered lightning to be one of the great mysteries of nature. Some ancient people believed that lightning and thunder were the weapons of the gods.

In reality, lightning is a flow of electricity formed high above the earth. A single flash of lightning 1.6 kilometres long has enough electricity to light one million light bulbs .

The American scientist and statesman, Benjamin Franklin, was the first to show the connection between electricity and lightning in 1752. In the same year he also built the first lightning rod (避雷针). This device protects buildings from being damaged by lightning.

Modern science has discovered that one stroke of lightning has a voltage (电压) of more than 15 million volts (伏特). A flash of lightning between a cloud and the earth may be as long as 13 kilometers, and travel at a speed of 30 million meters per second.

Scientists judge that there are about 2,000 million flashes of lightning per year. Lightning hits the Empire State Building in New York City 30 to 48 times a year. In the United States alone it kills an average of one person every day.

The safest place to be in case of an electrical storm is in a closed car. Outside, one should go to low ground and not get under tress. Also on,e should stay out of water and away from metal fences. Inside a house, people should avoid open doorways and windows and not touch wires or metal things.

With lightning, it is better to be safe than sorry.

小题1:People once thought lightning came from ________.

A．the gods

B．the earth

C．the sky

D．nature小题2:According to the passage what do you think all buildings need?

A．Metal fences.

B．Machines.

C．Electricity.

D．Lightning rods小题3:Lightning can travel ________.

A．as quickly as water

B．not so quickly as electricity

C．at very high speed

D．at very low speed小题4:Which of the following is NOT true?

A．In the U.S about one person per day dies from lightning.

B．Swimming during a thunder storm is a good idea.

C．The Empire State Building frequently gets hit by lightning.

D．A closed car is the best place to be during an electrical storm.

（2013•宁远县三模）生活中一些常见物质的PH如下，这些物质中碱性最强的是（　　）

A．橘子汁

B．西瓜汁

C．牙膏

D．肥皂水

工程质量事故处理依据应包括( )。

A．质量事故的实况资料

B．有关的合同文件

C．建设单位和监理单位的意见

D．相关的建设法规

E．相关的设计文件

救援专家概括出野外威胁生命的主要因素：严寒、酷热、烈日辐射、缺氧、脱水、外伤、中毒、饥饿、疾病、动物侵袭（）

鲁迅在《电的利弊》中说：“外国用火药制造子弹御敌，中国却用它做炮竹敬神；外国用罗盘针航海，中国却用它看风水……”中国古代科技在东西方的不同地位表明（）

A.科技能否产生巨大的经济和社会效益取决于社会环境

B.科技在不同的领域和范围对人类所做的贡献是不同的

C.火药和指南针的西传是中国跻身四大文明古国的重要标志

D.科学和愚昧只是人的意识对客观世界的不同反映