人类的日常生活中离不开合金，下列物质中不属于合金的是（）

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问题选择题

人类的日常生活中离不开合金，下列物质中不属于合金的是（　　）

A．用于门窗框架上的硬铝

B．用于冶炼金属铁的赤铁矿

C．用于生产铁锅的生铁

D．用于制造手术刀的不锈钢

答案

A、硬铝属于合金，是铝和铜、镁等物质混合在一起熔合而成的．

B、赤铁矿的主要成分是氧化铁，氧化铁属于氧化物，不属于合金．

C、生铁的主要成分是铁，还含有碳等物质，属于合金．

D、不锈钢的主要成分是铁，还含有碳、铬、锰等物质，属于合金．

故选：B．

阅读理解

阅读理解。

Parents Are Invited
To a Lecture On
Raising a Self-Disciplined Child
Help Your Child Become More
Responsible, Confident, and Lively
Presented by Dr Robert Brooks

1. Who is this lecture intended for?

A. Parents.
B. Children.
C. Robert Brooks.
D. Ginny Perkinson.

2. This lecture is mainly about how to _____.

A. become a writer
B. tell stories
C. sell a book
D. raise children

3. People can _____ if they have questions about the lecture.

A. visit Mr Williams
B. visit Dr Goldstein
C. call 4301-30327
D. call 404-231-8113

4. Raising a Self-Disciplined Child is the name of a _____.

A. newspaper
B. book
C. company
D. school

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阅读理解

“Humans should not try to avoid stress any more than they would shun food, love or exercise.” said Dr. Hans Selye, the first physician to document the effects of stress on the body. While here’s no question that continuous stress is harmful, several studies suggest that challenging situations in which you’re able to rise to the occasion can be good for you.

　　In a 2001 study of 158 hospital nurses, those who faced considerable work demands but coped with（设法处理） the challenge were more likely to say they were in good health than those who felt they couldn’t get the job done.

　　Stress that you can manage may also boost immune(免疫的) function. In a study at the Academic Center for Dentistry in Amsterdam, researchers put volunteers through two stressful experiences. In the first, a timed task that required memorizing a list followed by a short test, subjects believed they had control over the outcome. In the second, they weren’t in control: They had to sit through a gory(血淋淋的) video on surgical procedures. Those who did go on the memory test had an increase in levels of immunoglobulin A, an antibody that's the body’s first line of defense against germs. The video-watchers experienced a downturn in the antibody.

　　Stress prompts the body to produce certain stress hormones（荷尔蒙）. In short bursts these hormones have a positive effect, including improved memory function. “They can help nerve cells handle information and put it into storage,” says Dr. Bruce McEwen of Rockefeller University in New York. But in the long run these hormones can have a harmful effect on the body and brain.

“Sustained stress is not good for you,” says Richard Morimoto, a researcher at Northwestern University in Illinois studying the effects of stress on longevity(长寿), “It’s the occasional burst of stress or brief exposure to stress that could be protective.”