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【单选题】
In the illustrated circuit, us=50sin V, the active power (the average power)on a 5 Ω resistor is P1=I1.^2*R1=10 W, the active power of the resistor R2=10Ω is calculated by the equation P2=I2.^2*R2=20W. We can find out that I1=I2=sqrt(2)=1.414A,the total active power of this circuit is equal to P1+P2,that is 30W.The effective value of the voltage us is equal to 25*sqrt(2) V. Then the power factor cos φ =Ptotal/(Us*I) of the entire circuit is _________.Choose A,B,C or D.A.
0.3
B.
0.6
C.
0.8
D.
uncertain
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【简答题】低能 X 线的滤过通常选用( ) ,高能 X 线的滤过通常选用( ) 。
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A.
woman's head and a cat's body
B.
woman's head and a lion's body
C.
cat's head and a man's body
D.
woman's body and a cat's head
【简答题】vt.供给住宿;使适应;容纳;提供
【多选题】嫉妒是针对别人的成功而产生的一种心怀憎恨的羡慕之情。以下属于对嫉妒心理的调适方案的有_________。
A.
消极的自我暗示
B.
化嫉妒心理为竞争力
C.
以积极的心态看待自己和他人
D.
尊重别人,加强自身修养
E.
充实自己的生活
【简答题】Why are black cats bad? November 17 is an important day for black cats in Italy. An animal rights group has named that day “Black Cat Day” to stop the killing of thousands of the cats. Why do people t...
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