关于伤寒传染源以下哪项正确（） A.患者和带菌者都是传染源 B.患者从潜伏期起即可从

律师最早介入本诉讼的时间可以是在案件的( )。

A．侦查阶段

B．侦查终结后

C．起诉阶段

D．审判阶段

常见的可溶性酸碱盐在水中都可以电离．下列电离方程式中，正确的是（　　）

A．H₂SO₄=H₂²⁺+SO₄^2-

B．NaNO₃=Na⁺+NO₃^-

C．Ba（OH）₂=Ba²⁺+2O^2-+2H⁺

D．K₂MnO₄=2K⁺+MnO₄^-

阅读理解。

     When a cat is frightened, its heart starts beating faster, its muscles (肌肉) get tense, and there are changes

in the chemicals in its blood-stream. If the danger continues, it will defend itself, or it will run away as fast as

possible.

     Something like this also happens to people. When we are excited, angry, scared or aroused by other

emotions, our bodies go through many physical changes, all of which make us more alert (警觉的) and ready

to react. We, too, get ready to defend ourselves or run. Human beings, however, have a problem that animals

never face. If we give way to our feelings and let them take over, we can get into trouble. Have you ever said

something in anger-or hit somebody-and regretted it later? Have you ever shouted at a teacher, told somebody

you were lonely, or said you were in love, and then wished later you had kept your mouth shout? It isn't

always wise to express your feelings freely.

     Does this mean that it's smarter always to hide our feelings? No! If you keep your feelings of anger,

sadness, and bitterness hidden away or bottled up inside, your body stays tense. Physical illnesses can develop,

and you can feel disturbed badly inside, it can actually be bad for your health. You can try to treat emotions as

if they were bananas in the cupboard.

     You can hide them and you can pretend they don't exist, but they'll still be around. And at last you'll have to

deal with them, just like those bananas.

1. By taking cat as an example, the author wants to show us that _______.

A. animals can't control their feelings

B. people can't control their feelings

C. people physical reactions are like those of animals in a way

D. people's bodies go through many physical changes in certain situations, too.

2. It's mentioned in the text that human beings get into trouble because ______.

A. we are not as alert as animals

B. we sometimes can't control our feelings

C. we always do something wrong to other people

D. we don't pay attention to our physical changes

3. The author wants to tell us in the last two paragraphs that ______.

A. there's no way to deal with our feelings

B. we should put some bananas in a cupboard when we're angry or scared

C. feelings will gradually disappear when we hold them in

D. we should neither express our feelings freely nor hide the bad feelings inside

4. The author's purpose in writing this article is to _______.

A. tell us that it's pretty good to keep our feelings inside

B. give some advice on how to express our feelings freely

C. make us deal with our feelings in a wise way

D. make us know it isn't always good to express our feelings freely

凸、凹模间隙对冲裁件断面品质和尺寸精度有何影响？