问题 选择题

如图所示,在柱形容器中装有部分水,容器上方有一可自由移动的活塞。容器水面浮有一个木块和一个一端封闭、开口向下的玻璃管,玻璃管中有部分空气,系统稳定时,玻璃管内空气柱在管外水面上方的长度为a,空气柱在管外水面下方的长度为b,水面上方木块的高度为c,水面下方木块的高度为d。现在活塞上方施加竖直向下、且缓缓增大的力F,使活塞下降一小段距离(未碰及玻璃管和木块),下列说法中正确的是(     )  

        

A.d和b都减小

B.只有b减小

C.只有a减小

D.a和c都减小

答案

答案:C

活塞下降一小段距离,则容器中的气体体积减小,压强增大,对于木块露出的部分决定于上、下压强差,故c不变,对于玻璃管,浮力等于重力,排开水的体积不变,因压强增大,b变大,故a减小,C正确。

阅读理解

A Charlotte N.C. man was charged with first-degree murder of a 79-year-old woman whom police said he scared to death. Can the guy be held responsible for the woman’s death? Prosecutors (公诉人) said that he can under the state’s murder rule, which allows someone to be charged with murder if he or she causes another person’s death while committing or fleeing from a severe crime—even if he or she doesn’t kill someone on purpose.

But, medically speaking, can someone actually be frightened to death? We asked Martin Samuels, chairman of the neurology department at Brigham and Women’s Hospital in Boston.

Absolutely, no question about it.

The body has a natural protective method called the fight-or-flight response, which was originally described by Walter Cannon,chairman of Harvard University’s physiology department from 1906 to 1942. If, in the wild, an animal is faced with a life-threatening situation, the automatic nervous system responds by increasing heart rate, increasing blood flow to the muscles, and slowing digestion, among other things. All of this increases the chances of succeeding in a fight or running away from an aggressive beast. This process certainly would be of help to early humans. However, in the modern world there is obvious decline of the fight-or-flight response.

The autonomic nervous system uses the chemical messenger to send signals to various parts of the body to activate the fight-or-flight response. This chemical is poisonous in large amounts; it damages the organs such as the heart, lungs, liver and kidneys. It is believed that almost all sudden deaths are caused by damage to the heart. There is almost no other organ that would fail so fast as to cause sudden death.

By the way, any strong positive or negative emotions such as happiness or sadness can cause the same result. There are people who have died in excitement or in religious passion. There was a case of a golfer who hit a hole in one, turned to his partner and said, “I can die now”, and then he dropped dead.

小题1:What is Martin Samuels’ attitude to the possibility of being frightened to death?

A.Approval.

B.Disapproval.

C.Doubtful.

D.Indifferent.小题2:What can we learn about the fight-or-flight response according to the passage?

A.The fight-or-flight response was raised and proved by Martin Samuels.

B.It is a natural protective method that can’t be found in all creatures but humans.

C.The ancient humans had a better fight-or-flight response than modern ones.

D.The fight-or-flight response is beneficial to both our actions and organs.小题3:What activity can we infer is less likely to damage the organs?

A.Winning an unexpected fortune.

B.Missing a dead family member.

C.Watching a horror movie.

D.Listening to a sweet song.小题4:The purpose of the passage is ______.

A.to explain why people will die of a heart attack

B.to offer some advice on protecting us from heart failure

C.to compare different kinds of feelings to cause a death

D.to show strong emotions can cause a sudden death

问答题 简答题