设a为常数,则f(x)在区间(-∞,+∞)内的零点个数情况为( ).

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问题:

设a为常数

,则f(x)在区间(-∞,+∞)内的零点个数情况为( ).

考点:普通考研考研数学(三)考研数学三
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已知a、b是非零向量,指出下列等式成立的条件:

①|a|+|b|=|a+b|成立的条件是______;

②|a|+|b|=|a-b|成立的条件是______;

③|a+b|=|a-b|成立的条件是______;

④|a|-|b|=|a-b|成立的条件是______.

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如图是实验室用高锰酸钾制取氧气并收集氧气的装置图.回答下列问题:

(1)指出图中所标的仪器名称:A______,B______,C______,D______;

(2)指出图中的五处错误:①______,②______,③______,④______,⑤______.

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在梳理头发时,头皮屑大量脱落,好像下雨似的,这属于病理现象,在医学上称为()

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We can slow down aging. That is the message Dr. Shen Ziyin wants to give the world. And the Chinese doctor claims that he has found an answer to the problems of aging. His solution is a herbal medicine(草药)to slow the process of aging.

Dr. Shen Ziyin has been trained in Western medicine. At the same time he studied traditional Chinese medicine. And, he has been working for the past forty years to put together the best of both and find a cure for aging. He has taken a hint from the ancient Chinese medicine system called “Shen”.

According to Shen, it is the kidney(肾脏)which adjusts the functioning of the body as well as its aging process. It is responsible for the level of activity that the human bodies go through. Studies conducted by Dr. Shen show that herbal medicine based on the Shen system slows the aging process, says a report in the Telegraph newspaper. We notice that when people grow old, they have reduced strength, loss of hair, backache, weakness, wrinkles and so on. This happens because when people grow old, their bodies produce T-cells. These T-cells contain a particular substance called Fas. Fas makes the cells in the body destruct themselves.

So the only way to slow down aging is to slow the production of T-cells in the body. This can happen if people eat low calorie food. Then the body is not active enough to produce extra T-cells. But, is going hungry all the time a good price to pay for staying young? This is where Dr. Shen’s herbal medicine comes in. But how effective it will be, only time can tell.

小题1:How did Dr. Shen find the solution to the problem of aging?

A.By studying Western medicine.

B.By learning traditional Chinese medicine.

C.By combining both Western and Chinese medicine.

D.By doing research on both Western and Chinese people.小题2:What plays the most important role in keeping people young according to Shen?

A.Medical treatment.

B.Positive life attitude.

C.People’s good kidney.

D.Level of people’s activity.小题3:The reason why people become old is that    .

A.their bodies produce T-cells

B.they become weaker and weaker

C.they have reduced strength, loss of hair

D.their bodies are unable to fight diseases小题4:We can probably learn from the passage that    .

A.producing more low calorie food allows people to keep young

B.it remains unknown how effective Dr. Shen’s herbal medicine is

C.people should try to quicken the production of T-cells in the body

D.the more Chinese herbal medicine people drink, the better for health

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接种密度 inoculum density

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