问题 选择题

如图所示是古代战争中的“大炮”——抛石机,用它把大石块抛出去,打击远处的敌人,它实际是一个

A.费力杠杆

B.等臂杠杆

C.省力杠杆

D.斜面

答案

答案:A

抛石机实际是一个费力杠杆,因为它的阻力臂大于动力臂,选A

阅读理解

小题1:  When a starving man gets a meal, he begins to think about an overcoat; when an executive gets a new sports car, visions of country clubs and pleasure beats dance into view.

The many wants of mankind might be regarded as making up several levels.  小题2: .

The first and most basic level of wants involves food. Once this want is satisfied, a second level of wants appears: clothing and some sort of shelter. By the end of World War II these wants were satisfied for a great majority of Americans.   小题3: It included such items as automobiles and new houses.

By 1957 or 1958 this third level of wants was fairly well satisfied. Then, in the late 1950s a fourth level of wants appeared: the “life-enriching” level. While the other levels involve physical satisfaction-the feeding, comfort, safety, and transportation of the human body-this level stresses mental needs for recognition, achievement and happiness. It includes a variety of goods and services, many of which could be called “luxury” items. Among them are vacation trips, the best medical care, and entertainment. 小题4:    

On this level, a greater percentage of consumer spending goes to services, while on the first three levels more is spent on goods. Will consumers raise their sights to a fifth level of wants as their income increases, or will they continue to demand luxuries and personal services on the fourth level?

A fifth level probably would involve wants that can be achieved best by community action. Consumers may be spending more on taxes to pay for government action against disease, ignorance, crime and prejudice.  小题5: In this way, we can enjoy more fully the good things on the first four levels.

A.Then a third level appeared.

B.Human wants seem endless.

C.When there is money enough to satisfy one level of wants, another level appears.

D.There are several levels of wants in one’s life.E. At this stage, we now may seek to ensure the health, safety, and leisure.

F. Also included here are fancy foods and the latest styles in clothing.

G. Different people have different wants on each level.

单项选择题