【单选题】【消耗次数：1】
对人体危害最大的电流频率为( )。
①
20－30Hz
②
50－60Hz
③
80－90Hz
④
100－120Hz
参考答案：
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little difficult.
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The teacher assigned a lot.
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No problem.
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No way.
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Yes, you must
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No, you mustn’t.
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No, you don’t have to
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yes
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___________ was very not wise.
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Telling her the truth
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Having told her the truth
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Have told her the truth
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A. I like it.
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A. You are wonderful.
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A. That’s a good idea.
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very good
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Yes, it does.
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You looks very beautiful.
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It is a little tight.
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that
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One’s health should never be sacrificed for a need to work hard.
①
人的身体健康应该永不牺牲努力工作的需要
②
人永远不该为了努力工作的需要而牺牲身体健康。
③
人的身体健康永远不该为了需要努力工作而被牺牲。
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人的身体健康该为了需要努力工作而牺牲。
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①
fitly
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fitting
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fit
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I am very shy
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My job offers me high income
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I am very active in discussion
④
Ok