烧结使用的无烟煤含固定碳为（）。A．70～80% B．60～70% C．50～60%

外化（Externalization）

阅读理解。

     Every day, about one-quarter of American adults eat at fast-food restaurants. Cheap, tasty, and

convenient, fast food is rich in fat and calories, and it's low in fiber and nutrients. Thanks in large part

to fast food, half of America's adults and one-quarter of its children are fat, double the rate of a

generation ago. In the past two decades, eating habits have changed as people pay more attention to

their health. However, many Americans continue to eat red meat (beef in particular) as well as pork,

chicken and other foods. Although beer and wine are popular in most areas, many Americans abstain

from alcohol, because they think they will become healthier without drinking it. Various kinds of mineral

water are commonly available.

     Eating styles and habits vary between people of different backgrounds, but Americans generally eat

with the fork in the hand with which they write. A knife is used for cutting and spreading; otherwise, it is

laid on the plate or table. Fast foods, such as chips, fried chicken, hamburgers, and pizza, tend to be

eaten with the fingers. There is an obvious difference between what people may do at home or in a

fast-food restaurant, and how they act in a more formal restaurant. Because both parents often work

outside the home, some Americans are less likely to sit down as a family to eat once the children are

older and able to prepare their own food or serve themselves.

1. How many adults became fat after eating fast foods a generation ago?

A. 12.5% of them

B. 25% of them

C. 50% of them

D. 75% of them

2. American have changed their eating habits in the past twenty years because ______.

A. they want to keep healthy

B. economy develops faster

A. they have different backgrounds

D. they have to work outside

3. The underlined phrase "abstain from" in Para. 1 probably means ______.

A. feel like

B. get close to

C. suffer from

D. get rid of

4. We can infer from the passage ______.

A. some fast foods aren't eaten with tools in America

B. Americans always eat fried chicken with a knife

C. Americans prefer to eat outside than at home

D. Americans always go home having meals as a family

5. Which would be the best title of the passage?

A. Fast foods in the US.

B. Various cultures of the US.

C. Diet and eating in America.

D. Changes about Americans eating.

某三相对称负载，每相负载的X_L=30Ω，R=40Ω，△接法，电源的线电压为380V，则此电路的视在功率为（）

A.5kW

B.5kvar

C.8.66kV/A

D.8.66kW

返工后的检验项目，应重新进行质量验收。

何谓CO₂走短路（或称CO₂倒流）？