2012年“神九”的成功发射与安全返回，是我国航天事业的又一飞跃．“神九”飞船上

在-2，3，4，-5这四个数中，任取两个数相乘，所得的积最大的是______．

巴比妥类药物产生药效主要取决于

A．药物的空间构型

B．药物分子的电荷分布

C．C₆位取代基

D．C₅取代基

E．药物分子的大小

钢材根据加热保温和冷却方式的不同可将热处理分为退火、淬火、回火及表面热处理五种。

We often hear the phrase: "You've a greater chance of being struck by lightning." It is used to describe something that hasn't got much chance of happening. However, the common saying undermines(掩盖) the very real dangers of lightning.

Last Friday, at least 5 people were killed by lightning in Nepal(尼泊尔).

Lightning strikes are the second most common cause of deaths during natural disasters in the US. The first is floods. Around 400 people nationwide are struck by lightning each year, and of those, 73 people die. There are more people killed by lightning than by tornadoes and hurricanes.

Because lightning kills only one or two people at a time, its danger does not receive as much attention as other disasters.

So to raise awareness, the US has made June 22-28 National Lightning Safety Week. It aims to warn the public of the dangers of lightning and provide safety tips during thunderstorms.

"If you hear thunder, you are in danger of lightning," said Rocky Lopes, a disaster educator at the American Red Cross.

"Thunder means that lightning is close enough to hit you at any minute, so you should move indoors immediately and stay there until after the storm has ended. The single most important thing to remember is to seek a hiding place," Lopes said.

Summer is the high time for lightning storms, so when lightning strikes across the sky, remember these safety tips:

Stop working, fishing, swimming or playing in open fields.

If you can count less than ten seconds between a thunder and a lightning flash, take cover inside the nearest building.

Do not stand under a tree.

Get off bicycles or motorcycles.

Crouch down(蹲下)if there is no hiding place.

Avoid open spaces, wire fences, metal objects and electrical objects such as hair driers.

小题1:   The popular opinion about being struck by lightening is that ______.

A．there’s a greater chance for being killed by lightening than any other natural disaster

B．it is the most dangerous among all the natural disasters

C．the chance for a person to be struck by lightening is very small

D．it is impossible for people to be killed by lightening小题2:The average death rate of being struck by lightening in US is about _______.

A．18%

B．50%　　　　　

C．30%　　　　

D．73%小题3:thunder in             the open air______.

A．just stand by your bicycles and motorcycles

B．quickly find a place to go inside

C．count ten seconds between a thunder and a lightening

D．don’t have a hair drier in your hand小题4:According to the passage, which of the following is TRUE?

A．There are more people killed by tornadoes and hurricanes than by lightening in US each year.

B．There are on average 5 persons killed by lightening in Nepal each day.

C．The death rate of being stuck by lightening is much higher than by other natural disasters.

D．The National Lightening Safety Week is made to warn the public against the lightening.

扣件式钢管脚手架的永久荷载分项系数取( )，可变荷载分项系数取( )。

A．1.2；1.4

B．1.6；1.8

C．2.0；2.4

D．2.6；2.8