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问题 多选题

一列简谐横波在某时刻的波形如图所示，其振幅为A，图中所示的质点P从此刻开始，经四分之一周期通过的路程为S，关于S与A的关系，下列说法中正确的是（　　）

A．若波向右传播，则S＜A

B．若波向左传播，则S＜A

C．若波向左传播，则S＞A

D．若波向右传播，则S＞A

答案

若波向左传播，波形向左平移，则知质点P此刻向下运动，速度减小，在四分之一周期通过的路程S＜A．

若波向右传播，波形向右平移，则知质点P此刻向上运动，速度增大，在四分之一周期通过的路程S＞A．故BD正确，AC错误．

故选BD

完形填空

首字母填空（根据短文内容及首字母提示，补全空格内单词，使短文完整、通顺。（10）

Barack Obama, a black man, is the p___小题1:____ of the United States now. He was born o__小题2:__August 4th,1961, in Hawaii(夏威夷）and has lived in many places. His mother was from Kansas(堪萨斯州）and his father was from Kenya(肯尼亚）。 Obama went to Columbia University in New York and got a law degree at Harvard University in Massachusetts. His w__小题3:___ is Michelle Obama. She also w___小题4:___ as a lawyer(律师）and later worked for the University of Chicago. They have two young d___小题5:__. One is called Malia Ann, she is 12 years old. The o___小题6:__ one is Natasha, she is 9 years old.

Obama w__小题7:____ a book Dreams from my father. “I always live in the dream of my father and American people,” Obama once said. He was born in a poor family. And he was t__小题8:___ good care of by his grandparents when he was young. He also lived and worked in Africa. Then he got good e____小题9:___ in Harvard University. On November 4th,2012, he became the new president of A__小题10:____ for the next four years.
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单项选择题 A1型题

下列哪种试剂可使蛋白质的二硫键打开（）

A.溴化氢

B.2，4-二硝基氟苯

C.β巯基乙醇

D.碘乙酸

E.三氯醋酸
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