As the pace of life continues to increase, we are fast losing the art of relaxation. Once you are in the habit of rushing through lift, being on the go from morning till night, it is hard to slow down. But relaxation is essential for a healthy mind and body.                              

Stress is a natural part of everyday life and there is no way to avoid it. In fact, it is not the bad thing it is often supposed to be. A certain amount of stress is vital to provide motivation and give purpose to life. It is only when the stress gets out of control that it can lead to poor performance and ill health.                                                

The amount of stress a person can withstand depends very much on the individual. Some people are not afraid of stress, and such characters are obviously prime material for managerial responsibilities. Others lose heart at the first signs of unusual difficulties. When exposed to stress, in whatever form, we react both chemically and physically. In fact we make choice between "fight" or "flight" and in more primitive days the choice made the difference between life or death. The crises we meet today are unlikely to be so extreme, but however little the stress is, it involves the same response. It is when such a reaction lasts long, through continued exposure to stress, that health becomes endangered. Such serious conditions as high blood pressure and heart disease have established links with stress. Since we cannot remove stress from our lives (it would be unwise to do so even if we could), we need to find ways to deal with it.                                                               

People are finding less and less time for relaxing themselves because_____.                                                  

A. they do not know how to enjoy themselves                                       

B. they do not believe that relaxation is important for health      C. they are travelling fast all the time                                                    

D. they are becoming busier with their work  

According to the writer, the most important character for a good manager is his ________.   

A. not fearing stress                                                  B. knowing the art of relaxation         

C. high sense of responsibility                                   D. having control over performance   

Which of the following statements is true?  

A. We can find some ways to avoid stress.  

B. Stress is always harmful to people. 

C. It is easy to change the habit of keeping oneself busy with work.  

D. Different people can withstand different amounts of stress.  

In Paragraph 3, "such a reaction" refers back to_______. 

A. "making a choice between 'flight' or 'fight'"                                                         

B. "reaction to stress both chemically and physically"                                                     

C. "responding to crises quickly"

D. "losing heart at the signs difficulties" 

In the last sentence of the passage, "do so " refers to ______.     

A. "expose ourselves to stress"                               

B. "find ways to deal with stress" 

C. "remove stress from our lives"                   

D. "established links between diseases and stress"

As the pace of life continues to increase, we are fast losing the art of relaxation. Once you are in the habit of rushing through lift, being on the go from morning till night, it is hard to slow down. But relaxation is essential for a healthy mind and body.                              

Stress is a natural part of everyday life and there is no way to avoid it. In fact, it is not the bad thing it is often supposed to be. A certain amount of stress is vital to provide motivation and give purpose to life. It is only when the stress gets out of control that it can lead to poor performance and ill health.                                                

The amount of stress a person can withstand depends very much on the individual. Some people are not afraid of stress, and such characters are obviously prime material for managerial responsibilities. Others lose heart at the first signs of unusual difficulties. When exposed to stress, in whatever form, we react both chemically and physically. In fact we make choice between "fight" or "flight" and in more primitive days the choice made the difference between life or death. The crises we meet today are unlikely to be so extreme, but however little the stress is, it involves the same response. It is when such a reaction lasts long, through continued exposure to stress, that health becomes endangered. Such serious conditions as high blood pressure and heart disease have established links with stress. Since we cannot remove stress from our lives (it would be unwise to do so even if we could), we need to find ways to deal with it.                                                               

People are finding less and less time for relaxing themselves because_____.                                                  

A. they do not know how to enjoy themselves                                       

B. they do not believe that relaxation is important for health      C. they are travelling fast all the time                                                    

D. they are becoming busier with their work  

According to the writer, the most important character for a good manager is his ________.   

A. not fearing stress                                                  B. knowing the art of relaxation         

C. high sense of responsibility                                   D. having control over performance   

Which of the following statements is true?  

A. We can find some ways to avoid stress.  

B. Stress is always harmful to people. 

C. It is easy to change the habit of keeping oneself busy with work.  

D. Different people can withstand different amounts of stress.  

In Paragraph 3, "such a reaction" refers back to_______. 

A. "making a choice between 'flight' or 'fight'"                                                         

B. "reaction to stress both chemically and physically"                                                     

C. "responding to crises quickly"

D. "losing heart at the signs difficulties" 

In the last sentence of the passage, "do so " refers to ______.     

A. "expose ourselves to stress"                               

B. "find ways to deal with stress" 

C. "remove stress from our lives"                   

D. "established links between diseases and stress"

设平面α∥平面β，A、C∈α，B、D∈β，直线AB与CD交于点S，且AS=8，BS=9，CD=34，①当S在α、β之间时，SC=，②当S不在α、β之间时，SC=．

求由约束条件

x+y≤5 2x+y≤6 x≥0 y≥0

确定的平面区域的面积S和周长C．

数列{a_n}的前n项和记为S_n，前kn项和记为S_kn（n，k∈N^*），对给定的常数k，若

S(k+1)n

Skn

是与n无关的非零常数t=f（k），则称该数列{a_n}是“k类和科比数列”．
（1）已知Sn=

4

3

an-

2

3

(n∈N*)，求数列{a_n}的通项公式；
（2）在（1）的条件下，数列an=2cn，求证数列c_n是一个“1 类和科比数列”（4分）；
（3）设等差数列{b_n}是一个“k类和科比数列”，其中首项b₁，公差D，探究b₁与D的数量关系，并写出相应的常数t=f（k）．