问题 选择题

下面说法正确的是(  )

A.一切物体都具有内能

B.0℃的冰块不具有内能

C.抛在空中的球只具有机械能,不具有内能

D.一个物体的温度升高,它的内能不一定增加

答案

A、内能是物体内部大量分子无规则运动所具有的动能和分子的势能的总和,故符合题意;

B、对物体做功或让物体吸热,能使物体内能增大,温度不一定升高.例如0℃的冰化成0℃的水,具有内能,故B不符合题意;

C、一切物体都具有内能,抛在空中的球既具有机械能,又具有内能,故C不符合题意;

D、温度升高,物体吸热,吸收的能量用于增加分子势能,分子势能增加的,内能增加,故D不符合题意.

故选A.

问答题 简答题
单项选择题

It is all very well to blame traffic jams, the cost of petrol and the quick pace of modern life, but manners on the roads are becoming horrible. Everybody knows that the nicest men become monsters behind the wheel. It is all very well, again to have a tiger in the bank, but to have one in the driver’s seat is another matter altogether. You might tolerate the rude and inconsiderate driver, but nowadays the well-mannered motorist is the exception to the rule. Perhaps the situation calls for a "Be Kind to Other Drivers" campaign, otherwise it may get completely out of hand.

Road politeness is not only good manners, but good sense too. It takes the most cool-headed and good-tempered drivers to resist the temptation to revenge then subjected to uncivilized behavior. On the other hand, a little politeness goes a long way towards relieving the tensions of driving. A friendly nod or a wave of acknowledgement in response to an act of politeness helps to create an atmosphere of goodwill and tolerance so necessary in modern traffic conditions. But such acknowledgements of politeness are all too rare today. Many drivers nowadays don’t even seem able to recognize politeness when they see it.

However, improper politeness can also be dangerous. Typical examples are the driver who brakes violently to allow a car to emerge from a side street at some hazard to following traffic, when a few seconds later the road would be clear anyway; or the man who waves a child across a zebra crossing into the path of oncoming vehicles that may be unable to stop in time. The same goes for encouraging old ladies to cross the road wherever and whenever they want to.

A veteran driver, whose manners are faultless, told me it would help if motorists learnt to filter correctly into traffic streams one at a time without causing the total blockages (堵塞) that give rise to bad temper. Unfortunately, modern motorists can’t even learn to drive, let alone be well-mannered on the road. Years ago the experts warned us that the car-ownership explosion would demand a lot more give-and-take from all road users. It is high time for us to take this message to heart.

By "good sense" (Para. 2), the author means ().

A. the driver’s ability to understand and react reasonably

B. the driver’s prompt response to difficult and severe conditions

C. the driver’s tolerance of rude or even savage behavior

D. the driver’s acknowledgement of politeness and regulations