集中联锁以外的脱轨器及引向安全线或渺佳线的道岔,应装设()表示器。

题型:填空题

问题:

集中联锁以外的脱轨器及引向安全线或渺佳线的道岔,应装设()表示器。

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题型:填空题

等物质量浓度的HCN溶液与NaCN溶液等体积混合,混合液显碱性,下列说法错误的

A.c(CN) >c(Na+)>c(H+)>c(OH

B.c(Na+)>c(CN)>c(OH)>c(H+

C.c(Na+)+ c(H+)= c(CN)+ c(OH

D.2c(OH)+ c(CN)=2c(H+)+c(HCN)

题型:填空题

阅读理解。

     Louis Armstrong had two famous nicknames (绰号). 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 (影响) on the

world of music.

     Born in 1901 in New Orleans, be grew up poor, but lived among great musicians. Jazz was invented in the

city a few years before his birth. Armstrong often said, "Jazz and I grew up together."

     Armstrong showed a great talent (天赋) for music when he was taught to play the cornet (短号) at a boy's

home. In his late teens, Armstrong 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. Armstrong learned from the older musicians and soon became

respected as their equal.

     In 1922 he went to Chicago. There, the tale of Louis Armstrong begins. From then until the end of his life,

Armstrong was celebrated and loved wherever he went. Armstrong had no equal when it came to playing the

American popular song.

     His cornet playing had a deep humanity (仁爱) 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 (风格) and also one of the best-

known and most-admired people in the world. His death, on July 6, 1971, was headline news around the world.

1. Armstrong was called Pops because he _____.

A. looked like a musician

B. was a musician of much influence

C. showed an interest in music

D. travelled to play modern music

2. The third paragraph is developed _____.

A. by space

B. by examples

C. by time

D. by comparison

3. Which statement about Armstrong is true?

A. His tale begins in New Orleans.

B. He was born before jazz was invented.

C. His music was popular with his listeners.

D. He learned popular music at a boy's home.

4. 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

题型:填空题
如图所示,在x轴上方存在着垂直于纸面向里、磁感应强度为B的匀强磁场,一个不计重力的带电粒子从坐标原点O处以速度v进入磁场,粒子进人磁场时的速度方向垂直于磁场且与x轴正方向成120°角,若粒子穿过y轴正半轴后在磁场中到x轴的最大距离为a,则该粒子的比荷和所带电荷的正负是(  )

A.,正电荷

B.,正电荷

C.,负电荷

D.,负电荷

题型:填空题

空间某区域内存在着电场,电场线在竖直平面上的分布如图所示,一个质量为m、电量为q的小球在该电场中运动,小球经过A点时的速度大小为v1,方向水平向右,运动至B点时的速度大小为v2,运动方向与水平方向之间的夹角为α,A、B两点之间的高度差与水平距离均为H,则以下判断中正确的是(  )

A.若v2>v1,则电场力一定做正功

B.A、B两点间的电势差U=

m
2q
(
v22
-
v21
)

C.小球由A点运动至B点,电场力做的功W=

1
2
m
v22
-
1
2
m
v21
-mgH

D.小球运动到B点时所受重力的瞬时功率P=mgv2

题型:填空题

根据制度经济学理论,( )是分析经济制度的基本范畴。

A.价格
B.交易
C.资本
D.竞争

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