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【单选题】
超声波是频率超过人耳听觉的机械波,其频率范围为A.
高于20000 Hz
B.
1~10 MHz
C.
高于200 Hz
D.
0.15～15 MHz
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举一反三
【单选题】British bosses' shamelessness is revealed in all the following facts Except______.
A.
inefficiency of pension investment funds
B.
removal of final salary schemes
C.
denial of salary schemes to new employees
D.
demand for employees to pay more into pensions fund
【单选题】Which of the following facts that does NOT make it easy for the mother to take care of the business?
A.
She helped the father with the business before.
B.
She looked after the children.
C.
The speaker's other brother was helping with the business.
【单选题】助增电流的存在,对距离保护的影响是:
A.
测量阻抗增大，保护范围增大
B.
测量阻抗增大，保护范围缩小
C.
测量阻抗缩小，保护范围增大
D.
测量阻抗缩小，保护范围缩小
【单选题】助增电流的存在，对距离继电器的影响是( )
A.
使距离继电器的测量阻抗减小，保护范围增大
B.
使距离继电器的测量阻抗增大，保护范围减小
C.
使距离继电器的测量阻抗增大，保护范围增大
D.
使距离继电器的测量阻抗减小，保护范围减小
【简答题】According to the passage, the following facts are true EXCEPT that [A] the American public are now mainly concerned with their own risk. [B] Americans realize that has a powerful impact on their ...
【单选题】Which of the following is NOT one of the geographical facts about the Indian frontier?
A.
Melting snows.
B.
Stretch of deserts.
C.
Steep hillsides.
D.
Fertile valleys.
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