为什么链条锅炉燃烧过程各阶段的分界面都是斜面？

阅读理解。

    Sleep is very important. A person who does not sleep dies faster than a person who does not eat. We

spend about a third (1/3) of our lives in sleep. That's about 121 days a year!

    How much sleep do we need? We are all different. A baby needs 16 hours of sleep every day. Children

6 to 12 years old need an average (平均) of 10 to 12 hours of sleep. Teenagers need 9 to 10 hours of sleep.

An adult needs an average of 7 to 8 hours a night. There are some people who need only 3 hours of sleep.

Others need 10 hours of sleep. After the age of 50, the average sleep time goes down to 6.5 hours a night.

We need less sleep as we get older. 

    About one in three Americans has a problem with sleep. Many of these people cannot fall asleep. The

name of this problem is insomnia. Some people say, "I didn't sleep all night." But that's not really true.

They may sleep lightly and wake up several times. In the morning, they only remember the times they were

awake (醒着), so they think they were awake all night.

    This is not a new problem. Many famous people in history had insomnia. Some of these people had

special ideas to make them sleep. Benjamin Franklin had four beds. He moved from one to the other to fall

asleep. Mark Twain had a different way. He lay on his side across the end of the bed!

1. If you are thirteen years old, you need at least ______ hours of sleep. [ ]

A. 16

B. 12

C. 9

D. 7

2. What does "insomnia" mean in this passage? [ ]

A. No sleep.

B. Bad sleep.

C. Slow sleep.

D. Sleep with many dreams.

3. Which of the following is true according to the passage?[ ]

A. We will die soon if we don't sleep well.

B. The older we get, the less sleep we need.

C. We can tell a person's age from his sleep time.

D. Famous people move from one bed to the other to fall asleep.

4. Which would be the best title for this passage? [ ]

A. Sleep More!

B. Go to Sleep!

C. Age and Sleep Time.

D. Famous People and Sleep.

秦朝统一后确立专制集权制度。以下关于“秦朝统治机制示意图”，表述不正确的是 （  ）

A．秦始皇开始建立皇帝制度和三公九卿制度

B．中央机构职责明确，形成了决策、审议、行政为一体的中央行政体制

C．秦朝开始在全国废除分封制，将郡县制度全国推广

D．秦律的颁行不能改变秦朝仍是人治社会的现实

一个工人生产了81个同样的零件。一个内部有砂眼的原材 料也做成了成品，这是一个次品，为了保证产品质量，一定要把它找出来这个次品虽然从外表上看不出来，但是它内有空洞，比别的零件轻，一定可以用天平把它称出来。

（1）如果让你帮忙，用天平称，你用几次保证可以找出次品？

（2）你能称4次就能保证把它找出来吗？该怎样称？你会用图示的方法表示称的过程吗？ 

（3）如果天平两边各放40个零件，称一次有可能称出来吗？

居民企业在一个纳税年度内，转让技术使用权所得不超过500万元的部分，免征企业所得税；超过500万元的部分，减半征收企业所得税。（　）

妊娠后，肢体面部发生肿胀，经卧床休息，一夜而不能消失者，称为（）

A.子满

B.子痫

C.子肿

D.子悬

E.子烦