什么是颗粒度？

阅读理解。

     Teen Dating can be fun if you are aware(知道)of its pros and cons and are also aware of the ways

to protect yourself. There are a couple of suggestions you would like to know before you are out for

dating.

     Do not go out for dating with somebody whom you have seen only a few times and does not know

much about him or her.

     Before leaving on a date,know the exact plans for the evening and make sure a parent or friend

knows these plans and what time to expect you home. Let your date know that you are  expected to

call or tell that person when you get in.

     Similarly, if you leave a party with someone you do not know well,make sure you tell another person

you are leaving and with whom. Ask a friend to call and make sure you arrive home safely.

     No matter how good the person appears to you,trust your inner instincts(直感). If a situation makes

you uncomfortable,try to stay calm and think of a way to remove yourself from the  situation without

letting your date realize what is going on in your mind.

     Always stay firm,straightforward and clear in your relationships,thoughts,decisions and judgments.

Never let a doubt come to your mind or face when out for dating. If you are firm and  clear in your

communication,your date will always be careful in dealing with you.

     You should think ahead about ways to be safe if you are in a dangerous or potentially(潜在)

dangerous relationship. Adults,like parents,teachers,counselors,can be trusted in such cases.

1. Which of the following is forbidden when dating according to the passage?

A. Knowing the plan for the evening.

B. Telling your parents about the date.

C. Going out for dating with a stranger.

D. Telling the person you date that your parents know about the date.

2. The underlined word"date"in the third paragraph might mean

A. a time    

B. a plan    

C. a person

D. a place

3. If you feel uncomfortable,you should__________.

A. call your parents

B. leave as soon as possible

C. speak out what you are thinking

D. trust the person you're dating with

4. The best title for this passage might be

A. Be careful with your friends

B. Never go out dating

C. Safety measures for teen dating      

D. Dating out is always dangerous

三羧酸循环最重要的生理意义是（）。

A.产生CO2供机体生物合成需要

B.产生H2O供机体利用

C.脂肪合成的主要途径

D.消除乙酰辅酶A，防止其在体内堆积

E.糖、脂肪和蛋白质彻底氧化的共同途径

市场主体具有经济上的( )。

A．局限性

B．独立性

C．保守性

D．战略性

对于化学烧伤的伤口，一定还要将残留化学物质彻底清洗干净后，方可进行后续处置。

（）是指能接受油墨或吸附色料并呈现图文的各种物质。

A、印版

B、承印物

C、底片

D、原稿