淬火和回火的钢针相比( ) A.硬度增强 B.可塑性增强 C.韧性不变 D.韧性

题型:选择题

问题:

淬火和回火的钢针相比(  )

A.硬度增强

B.可塑性增强

C.韧性不变

D.韧性增强

考点:合金
题型:选择题

阅读理解

      Are you preparing for a big test? If so, you may want to play some basketball in between hitting the

books. Doctors are starting to find more and more information that suggests a connection between

exercise and brain development. Judy Cameron, a scientist at Oregon Health and Oregon Health and

Science University, studies brain development. According to her research, it seems that exercise can

make blood vessels(管), including those in the brain, stronger and more fully developed. Dr. Cameron

claims this allows people who exercise to concentrate better. As she says, "While we already know that

exercise is good for the heart, exercise can really cause physical changes in the brain."

     The effects of exercise on brain development can even be seen in babies. Babies who do activities

that require a lot of movement and physical activity show greater brain development than babies who

are less physically active. With babies, even a little movement can show big results. Margaret Barnes,

a pediatrician(儿科医生), believes in the importance of exercise. She thinks that many learning

disabilities that children have in elementary school or high school can be traced back to a lack of

movement as babies. "Babies need movement that stimulates their five senses. They need to establish a

connection between motion and memory. In this way, as they get older, children will begin to associate

physical activity with higher learning," says Margaret.

     Older people can beef up their brains as well. Scientists from 11 universities studied a group of

seniors ranging in age from seventy to seventy-nine. Their study showed a short-term memory increase

of up to 40 percent after exercising just three hours a week. The exercise does not have to be very

difficult, but it does have to increase the heart rate. Also, just like the motion for infants (婴儿), exercise

for older people should involve some complexity. Learning some new skills or motions, such as with

yoga or tai-chi, helps to open up memory paths in the brain that may not have been used for a long time.

     For most people, any type of physical activity that increases the heart rate is helpful. The main goal is

to increase the brain's flow of blood. And your brain can benefit from as little as three hours of exercise

a week.

1. What is the best title of this passage?

A. How to exercise                        

B. How exercise helps the brain

C. How to get good scores on a test            

D. How the brain can change

2. According to the reading, what is the connection between exercise and brain development?

A. Exercise makes us stupid.                

B. The brain needs special mental exercise.

C. The more exercise, the bigger the brain.      

D. Physical exercise helps us think better.

3. The mini amount of exercise required to gain any benefit is ________.

A. three hours per week                    

B. 40 hours per week

C. three hours per day                      

D. 40 hours per month

4. Why does the author think that yoga is fit for seniors?

A. It is easy to learn.                      

B. It can be done in groups.

C. It does not increase the heart rate.          

D. It includes learning new motions.

题型:选择题

下列混合固定液不含有重铬酸钾的是()。

A.Bouin液

B.Zenker液

C.Maximov液

D.Helly液

E.Regaud液

题型:选择题

自我服务偏见行为有助于保护或提高我们的自尊。

题型:选择题

乳酶生是()

A、胃肠解痉药

B、抗酸药

C、干燥活乳酸杆菌制剂

D、生乳剂

题型:选择题

读我国不同地区河流径流量过程示意图(下图),回答下列各题。

图中反映华北地区河流径流量变化特征的是()

A.甲

B.乙

C.丙

D.丁

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