问题 选择题

在下列所述的物体的运动情况中,不可能出现的是(  )

A.物体在某一时间速度很大,而加速度为零

B.物体在某一时间速度很小,而加速度很大

C.运动的物体在某一时刻速度为零,而加速度不为零

D.做变速直线运动的物体,加速度的方向与运动的方向相反,它的速度在增大

答案

A、物体在某一时间速度很大,加速度为零是可能,比如物体做匀速直线运动.故A错误.

B、物体在某一时间速度很小,加速度很大是可能的,比如火箭刚点火时,速度很小,但加速度很大.故B错误.

C、运动的物体在某一时刻速度为零,加速度不为零是可能的,比如竖直上抛的物体到达最高点时.故C错误.

D、做变速直线运动的物体,加速度的方向与运动的方向相反,它的速度在减小,不可能增大.故D正确.

故选D

选择题
单项选择题

Imagine a world in which there was suddenly no emotion—a world in which human beings could feel no love or happiness, no terror or hate. Try to imagine the consequences of such a transformation. People might not be able to stay alive, knowing neither joy nor pleasure, anxiety nor fear, they would be as likely to repeat acts that hurt them as acts that were beneficial. They could not learn, they could not benefit from experience because this emotionless world would lack rewards and punishments. Society would soon disappear, people would be as likely to harm one another as to provide help and support. Human relationships would not exist, in a world without friends or enemies, there could be no marriage, affection among companions, or bonds among members of groups. Society’s economic underpinnings (基础, 支柱) would be destroyed, since earning $10 million would be no more pleasant than earning $10, there would be no incentive to work. In fact, there would be no incentives of any kind. For as we will see, incentives imply a capacity to enjoy them.

In such a world, the chances that the human species would survive are next to zero, because emotions are the basic instrument of our survival and adaptation. Emotions structure the world for us in important ways. As individuals, we categorize objects on the basis of our emotions. True we consider the length, shape, size, or texture, but an object’s physical aspects are less important than what it has done or can do to us—hurt us, surprise us, anger us or make us joyful. We also use categorizations colored by emotions in our families, communities, and overall society. Out of our emotional experiences with objects and events comes a social feeling of agreement that certain things and actions are "good" and others are "bad", and we apply these categories to every aspect of our social life—from what foods we eat and what clothes we wear to how we keep promises and which people our group will accept. In fact, society exploits our emotional reactions and attitudes, such as loyalty, morality, pride, shame, guilt, fear and greed, in order to maintain itself. It gives high rewards to individuals who perform important tasks such as surgery, makes heroes out of individuals for unusual or dangerous achievements such as flying fighter planes in a war, and uses the legal and penal system to make people afraid to engage in antisocial acts.

It can be inferred from the passage that the economic foundation of society is dependent on ().

A. the ability to make money

B. the will to work for pleasure

C. the capacity to enjoy incentives

D. the categorizations of our emotional experiences