问题 问答题 简答题

简述视频监控系统中摄像机的照度含义。

答案

参考答案:照度是反映光照强度的一种单位,其物理意义是照射到单位面积上的光通量。照度的单位是每平方米的流明(Lm)数,也叫做勒克斯(Lux):1Lux=1Lm/平方米,上式中,Lm是光通量的单位,其定义是纯铂在熔化温度(约1770℃)时,其1/60平方米的表面面积于1球面度的立体角内所辐射的光量。摄像机的照度越低,摄像机的核心部件CCD可以具有更高感光度,对外界光线的敏感程度会大大提高,这样,即使在非常暗的环境下,这种摄像机通常可以看到人眼看不到的物体。

阅读理解

阅读理解。

       A friend of mine asked me the question, "Who said life was going to be fair, or that it was even meant

to be fair?" Her question was a good one. It reminded me of something I was taught as a youngster: Life isn't

fair. It's a bummer, but it's absolutely true. 

      One of the mistakes many of us make is that we feel sorry for ourselves, or for others, thinking that life

should be fair, or that someday it will be. It's not and it won't. One of the nice things about surrendering (承认)

to the fact that life isn't fair is that it keeps us from feeling sorry for ourselves by encouraging us to do the

very best we can with what we have. We know it's not "life's job" to make everything perfect it's our own

challenge. Surrendering to this fact also keeps us from feeling sorry for others because we are reminded that

everyone is dealt a different hand; everyone has his own strengths and problems in the process of growing up,

facing the reality and making decisions; and everyone has those times that they feel cheated or unfairly treated.

     The fact that life isn't fair doesn't mean we shouldn't do everything in our power to improve our own lives

or the world as a whole. Instead, it suggests that we should. When we don't recognize or admit that life isn't

fair, we tend to feel pity for others and for ourselves. Pity is a self-defeating (自我挫败的) emotion that does

nothing for anyone, except to make everyone feel worse than they already do. When we do recognize that life

isn't fair, however, we feel compassion (同情) for others and for ourselves. And compassion is a heatfelt

emotion that delivers loving-kindness to everyone it touches. The next time you find yourself thinking about

the unfair world, try reminding yourself of this very basic fact. You may be surprised that it can push you out

of self-pity and into helpful action.

1. The words "a bummer" in the first paragraph probably means ___.

A. a chance

B. a disappointment

C. a choice

D. an embarrassment

2. Which statement is TRUE according to the passage?

A. We cannot just feel sorry, but take actions.

B. We may feel worse when we realize the unfaimess.

C. Life will become fair someday through our great efforLs.

D. Pity is a self-defeating emotion delivering loving-kindness.

3. The best title for the passage is___.

A. Push You out of Self-pity

B. Face the Problems in Your Life

C. Encourage Yourself to Do the Best

D. Surrender to the Fact that Life Isn't Fair

单项选择题