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问题 单项选择题

关于密度分辨力的叙述，不正确的是（）

A.密度分辨力主要受噪声的影响

B.受光通量的影响

C.重建算法可影响密度分辨力

D.高分辨力重建算法改为软组织平滑的算法，则可减少噪声，使图像的密度分辨力提高

E.受焦点尺寸的影响

答案

参考答案：E

解析：空间分辨力受焦点尺寸的影响。

单项选择题

B


Each year there is an increasing number of cars on roads and street are millions of new cars are produced. One out of every six Americans works at putting together the parts of cars, driving trucks, building roads of filling cars with gas. Americans won’t live without cars!
Most Americans find it hard to think what life would be without a car. However some have realized the serious problem of air pollution by cars. The polluted air is poisonous(有毒的) and dangerous to health.
One way to get rid of(排除)the polluted air is to build a new kind of car. That’s what several of the large car factories are trying to do. But to build a clean car is easier said than done. Progress in this field has been slow.
Another way is to take the place of the car engine(发动机) by something else. Engineers are now working on some new cars. Many makers believe that it will take years to develop a practical model that pleases man.
To prevent the world from being polluted by cars, we’ll have to make some change in the way many of us live. Americans, for example, have to cut down on the number of their cars. They are encouraged to travel and go to work by bike. Riding a bike is thought to help keep the air clean.
But this change does not come easily — a large number of workers may find themselves without jobs if a car factory closed down. And the problem of air pollution would become less important than that of unemployment(失业).
Although cars have brought us a better life, they have also brought us new problems.

If the number of cars is cut down, the most serious problem to American workers is to ______.

A．have no work to do

B．improve their environment

C．make their factories richer

D．go to work by bike
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