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【单选题】
绳索的约束反力的方向为________。A.
沿着绳索的中心线且指向物体
B.
沿着绳索的中心线而背离物体
C.
沿着绳索中心线的垂直方向
D.
任意方向
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反馈参考答案：
举一反三
【单选题】— Do you know sound travels very fast? — Yes. But light travels sound.
A.
as fast as
B.
a little faster than
C.
much faster than
D.
slower than
【判断题】抗日战争期间，日本侵占南京30多万军民被屠杀，杀的天地为之改色，他们杀了我们还说我们是“东亚病夫”天理何在啊!真情哪有啊!不就是我们穷吗!我们弱吗!我们不团结吗!所以我们不能忘记：中国人这段痛苦的耻辱历史。()
A.
正确
B.
错误
【单选题】一台电脑由数以万计的人参与制,他们当中大多数不相识,让电脑得以形成的无数行为更没有任何人规定或指挥,从电脑的制造中可以看出( )。
A.
企业联合能提高资源利用效率
B.
社会分工促进了生产效率提高
C.
市场对资源配置起决定性作用
D.
社会道德在市场中起支配作用
【单选题】How do we judge whether a sound is a vowel or a consonant?
A.
Whether there is sound.
B.
Whether there is obstructions.
C.
Whether there is air flow.
D.
Whether the sound is loud or not.
【单选题】How do we hear the amplified sound?( )
A.
Sound waves are picked up by a speaker and converted to a small analog voltage called the audio signal, then the voltage are sent to the microphone.
B.
Sound waves are picked up by a microphone and converted to a small analog voltage called the audio signal, then the voltage are sent to the speaker.
C.
Sound waves are picked up by a microphone and converted to a small digital voltage called the audio signal, then the digital voltage are sent to the speaker.
【单选题】How do we hear the amplified sound ?
A.
Sound waves are picked up by a speaker and converted to a small analog voltage called the audio signal, then the voltage are sent to the microphone.
B.
Sound waves are picked up by a microphone and converted to a small analog voltage called the audio signal, then the voltage are sent to the speaker .
C.
Sound waves are picked up by a microphone and converted to a small digital voltage called the audio signal, then the digital voltage are sent to the speaker
D.
。
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