问题
单项选择题
单相桥式全控整流电路的优点是提高了变压器的利用率，不需要带中间抽头的变压器，且( )。
A．减少了晶闸管的数量
B．降低了成本
C．输出电压脉动小
D．不需要维护
答案
参考答案：C
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单相桥式全控整流电路的优点是提高了变压器的利用率，不需要带中间抽头的变压器，且( )。
A．减少了晶闸管的数量
B．降低了成本
C．输出电压脉动小
D．不需要维护
参考答案：C
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| Let's look at a fly, and see where it flies. First, it flies out 1 the window. 2 , it stands on 3 dirty things in the street, and then it flies back to the house and walks over your 4 . When a fly walks on the dirty things in the street, its 5 have got some germs 6 them. When the fly walks on your food with its dirty feet, it 7 the germs on your food. What can you 8 this? First, we learn that we mustn't leave dirty things in the street or on the ground near 9 . Second, we learn that all food must be covered so that flies may not 10 it. Third, we learn that flies often carry germs and we must kill them as soon as we see them. | ||||
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