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问题 选择题

一物体自t=0时开始做直线运动，其速度图线如图所示．下列选项不正确的是（　　）

A．在0～6s内，物体离出发点最远为35m

B．在0～6s内，物体经过的路程为40m

C．在0～4s内，物体的平均速率为7.5m/s

D．在5～6s内，物体所受的合外力做负功

答案

A、在0-5s，物体向正向运动，5-6s向负向运动返回．故5s末离出发点最远．根据速度图象的“面积”大小等于位移大小，得到最远距离为s=

(2+5)×10
2
m=35m．故A正确；

B、由面积法求出0-5s的位移x1=35m，5-6s的位移x2=-5m，总路程为40m．故B正确．

C、由面积法求出0-4s的路程为s=30m，平度速率为：v=

s
t
=7.5m/s．故C正确；

D、由图象知5～6s过程物体加速，合力和位移同向，合力做正功．故D错误．

本题选错误的，故选D

单项选择题

柴油机燃烧的最高温度点出现在（）

A.滞燃期

B.缓燃期

C.速燃期

D.后燃期
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单项选择题

Louis Armp had two famous nicknames. Some people called him Bagamo. They said his mouth looked like a large bag. Musicians often called him Pops, as a sign of respect for his influence on the world of music.
Born in 1901 in New Orleans, he grew up poor, but lived among great musicians. Jazz had been invented in the city a few years before his birth. Armp often said, "Jazz and I grew up together. "
Armp showed a great talent for music when he was taught to play the comet at a boy’s home. In his late teens, Armp began to live the life of a musician. He played in parades, clubs, and on the steamboats that traveled on the Mississippi River. At that time, New Orleans was famous for the new music of jazz and was home to many great musicians. Armp learned from the older musicians and soon became respected as their equal.
In 1922 he went to Chicago. There, the tale of Louis Armp began. From then until the end of his life, -Armp was celebrated and loved wherever he went. Armp had no equal when it came to playing the American popular song.
His cornet playing had a deep humanity and warmth that caused many listeners to say, "Listening to Pops just makes you feel good all over. " He was the father of the jazz style and also one of the best known and most admired people in the world. His death, on July 6th 1971, was headline news around the world.

Which would be the best title for the text

A．The Invention of the Jazz Music

B．The Father of the Jazz Style

C．The Making of a Musician

D．The Spread of Popular Music
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