两列水波发生干涉,在某时刻,M点是波峰与波峰相遇处,N点是波谷与波谷相遇处,P点

题型:选择题

问题:

两列水波发生干涉,在某时刻,M点是波峰与波峰相遇处,N点是波谷与波谷相遇处,P点的位移为零,Q点是波谷与波峰相遇处,则(   )
A.M、N两点振动一定最强,P、Q两点振动一定最弱
B.M点振动最强,N、Q振动最弱,P点可能最强也可能最弱
C.M、N点振动最强,Q振动最弱,P点可能最强也可能最弱
D.四个点都可能是振动加强点
考点:波的干涉波的衍射
题型:选择题

窄带 ISDN 提供的“一线通”业务将 B 信道和 D 信道合并为一个数字信道使用,其 速率为______。

A.512kbps

B.144kbps

C.128kbps

D.64kbps

题型:选择题

All the people around the world have the same simple dream _____ they will always live in peace.

A.that

B.which

C.where

D.when

题型:选择题

阅读理解。

     People often talk as if shyness is a disease or mental condition that can be cured.  I prefer to think of it as an emotional disability. It's something we are bom with and something we carry with us in our entire lives. There are too many people,however,who seem to be determined to find some ways of doing away with their shyness. In my opinion,it's a waste of time. I don't mean that we should do nothing about it;quite the

contrary,I think we need to separate the basic fact of shyness from our ability to take part in a social

environment.

      Look at one of the most famous shy people of them all,Johnny Carson. This man is painfully shy,yet

for decades he made a living talking and associating(交往) with different people every night,in front of a

national audience.  Carson has never done away with his shyness,but he has successfully found a way to

deal with it to the extent that he could be, not just a talk show host,but a legend(传奇) among talk show

hosts.  Look also at Sally Fields,who has recently admitted her problem with shyness. This is a woman

who has appeared in many films,TV shows and interviews,yet in her early years she was so shy that she

tumed down a lunch invitation from Jane Fonda because she was terribly afraid of meeting her.

      I guess that our shyness is there because each of us is bom with some msecurity(不安全感) and this

insecurity prevents us from reaching out to others the way people with a more open personality do. As we grow up and become adults,we allow our social skills to grow and develop. But we are still stuck in kindergarten or elementary school or wherever it was when our shyness took root in our soul.

1. In the author's view,shyness can be explained as ______.

A. a disease that can be easily cured        

B. a not very normal mental condition

C. an emotional disability                    

D. something we pick up after birth

2. The author believes it's a waste of time to _____.

A. develop a healthy personality            

B. talk with as many people as possible

C. study where shyness comes from      

D. look for ways to do away with one's shyness

3.  Which of the following is TRUE of Johnny Carson?  

A. He dared to speak in front of a national audience.

B. He did away with his shyness carefully.

C. He was described as a hero in some legend books.

D. He failed to become a good talk show host.

4. The passage tells us that Sally Fields was ______

A. proud all the time                            

B. impolite when young

C. shy in her early years                        

D. close to Jane Fonda

5. The author thinks that our shyness is there because ______.

A. we are not open enough                    

B. we don't feel safe at heart

C. we try to reach out to others all the time    

D. we lack certain social skills

题型:选择题

一般炒炭多用的火力是()

A.武火

B.中火

C.文火

D.先文火后中火

E.先中火后武火

题型:选择题

植物生命活动调节的基本形式是激素调节,下表是植物不同部位各种激素的相对浓度,请根据有关信息分别回答下列问题:

上表中的激素可以促进种子萌发的是(),种子萌发后,各种激素在不同器官处的含量是不同的,根据上表比较茎尖和伸长茎中各种激素的含量,从细胞角度分析植物的生长,说明生长素和赤霉素主要通过促进(),从而促进生长;细胞分裂素主要通过促进(),而促进生长。

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