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【单选题】
三相桥式整流电路,电阻性负载时,当触发角( )时,整流输出电压平均值Ud=2.34U2 COSα。A.
α≤30 o
B.
α≤60 o
C.
α≤90 o
D.
α= 90 o
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A.
much
B.
too
C.
so
D.
very
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much
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very
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正北方
B.
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A.
Being published
B.
Published
C.
Publishing
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To be published
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【简答题】________ as it was at such a time, his work attracted much attention. A) Being published B) Published C) Publishing D) To be published
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