下列关于声音的产生和传播的说法中，正确的是（ ）

【名词&注释】

障碍物(obstacle)、新中国成立以来(since the founding of new china)、杰出贡献(outstanding contribution)、突出贡献(outstanding contribution)、中宣部、评选活动(selecting activity)、环境温度的影响(environment temperature effect)、联合组织(united organization)、模范人物、声音的传播速度

[单选题]下列关于声音的产生和传播的说法中，正确的是（ ）

A. 声音都是靠空气来传播的
B. 只要物体振动，就能听到声音
C. 回声是声音被障碍物反射而形成的
D. 声音的传播速度不受周围环境温度的影响^{(environment temperature effect)}

查看答案&解析查看所有试题

学习资料：

[单选题]有两个电阻，阻值分别为30和10Ω，把它们串联起来，其总电阻是

A. 40Ω
B. 30Ω
C. 20Ω
D. 7.5Ω

[单选题]由中宣部等11个部门联合组织^{(united organization)}开展的“100位为新中国成立做出突出贡献的英雄模范人物和100位新中国成立以来感动中国人物”评选活动，于2009年9月10日隆重揭晓。回答20～21题。20．下列“双百”人物中，为我国科技强军做出杰出贡献的是

A. 雷锋
B. 王进喜
C. 袁隆平
D. 邓稼先

[单选题]III阅读理解（20分）A

A. My uncle thinks this is because cars are like their drivers． He says: "Rich people have expensive cars，big people have large cars，and old people drive old cars． "But I don-t agree with him．
B. She drives only to the bank on Tuesdays． She never drives more than 30 kilometers an hour． Do you think Mrs Hill has a very old and small car? No! Her car is new．lt-s very large，and it can g0 200 kilometers an hour!
C. He draws beautiful pictures with lots of colors． But his car is black! Mrs Bates has a very，very old car．lt often has engine trouble． Does she drive that kind of car because she is poor? No，she has four factories and two million dollars in the bank． My aunt Mary has a very small car． Every Sunday，she．drives to the country with her husband，her three children，her mother and their dog．
D. Do you agree with my uncle? Maybe your family have cars． Do you want to say something about them?'
E. What does the writer-s uncle think of cars and their drivers?
F. Big people drive small cars
G. Old people drive new cars．
H. Poor people have expensive cars．
I. Rich people have dear cars．

[单选题]6． His name is James， but he calls ________Jim．

A. his
B. himself
C. him
D. /

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