静态稳定性

Many of us don’t pay much attention to the importance of eye care. It is said that if you take care of your body, then you can surely be healthy. That is why our eyes should be given a lot of care. Natural eye care should be put in a number one place.

There are several causes leading to poor eyesight like not enough food, genes (基因) and aging (老化). Televisions, computers and reading are also the causes of having poor eyesight. If you happen to work in front of the computer, it is best to take a break every once in a while. Something dirty can cause redness and they will make you feel uncomfortable. It is bad for your eyes, too. If this happens, the best way is to clean your eyes by using cold water. You must also try your best to protect your eyes from harmful things. For example, sunglasses are not just for fashion but they can also serve as a great way to protect your eyesight form UV rays.

Eating healthy foods will do good to your eyesight. Remember that vitamins A, C and E are good for eyes. Try to eat food groups that have these vitamins. And you should do eye exercises because exercise protects your eyesight, too. If a person exercises regularly (定期地) and eats the right kind of food, his eyes will stay in good condition for a long time.

All above are natural ways of eye care that help us keep healthy eyes. Being happy all the time can be helpful to a person’s eyesight, too. In a world, eye care is very important, no matter how old a person is.

小题1:_____ is the most important way to protect our eyes.

A．Natural eye care

B．Taking medicine

C．Seeing the doctor

D．Being happy all the time小题2:All the following causes can lead to bad eyesight except _______.

A．age

B．height

C．reading

D．computers小题3: What should you do if you have to work in front of the computer?

A．Eat healthy foods.

B．Clean the eye by using cold water.

C．Wear a pair of sunglasses.

D．Have a rest after working for a while.小题4:What do the underlined words “UV rays”mean?

A．沙尘

B．闪电

C．紫外线

D．超声波小题5: Which is the best title of the passage?

A．Ways of Eye Care

B．Ways of Eye Exercises

C．Ways of Being Happy

D．Ways of Being Healthy

下图是形成北半球近地面的各种力的示意图，下列说法正确的是

A．图中③是使风向向右偏转的地转偏向力

B．图中②是使风力增强的地面摩擦力

C．图中③是使风向发生变化的水平气压梯度力

D．图中①是指大气产生运动的水平气压梯度力，方向总是由南向北

质量为m的木块从半球形的碗口下滑到碗底的过程中，如果由于摩擦力的作用，使得木块的速率不变，那么[ ]

A．下滑过程中木块加速度为零

B．下滑过程中木块所受合力大小不变

C．下滑过程中木块受合力为零

D．下滑过程中木块所受的合力越来越大

如图，表示可燃物易燃烧的点是（　　）

A．a

B．b

C．c

D．d

中国在（）年成功爆炸了第一颗原子弹。

A.1949

B.1955

C.1964

D.1970