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【单选题】
负载1(感性)与负载2(容性)并联接在正弦交流电源上，它们的视在功率依次为S 1 和S 2 ，有功功率依次为P 1 和P 2 ，无功功率依次为Q 1 和Q 2 。关于电路总视在功率s的表，正确的为( )。A.
S=S 1 +S 2
B.
S 2 =(P 1 +P 2 ) 2 +(|Q 1 |+|Q 2 |) 2 ；
C.
S 2 =(P 1 +P 2 ) 2 +(|Q 1 |-|Q 2 |) 2
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反馈参考答案：
举一反三
【单选题】关于反馈作用的叙述,错误的是
A.
是保证调节精确性的重要机制
B.
各种调节方式均存在有反馈作用
C.
正反馈在机体功能调节中表现较突出
D.
负反馈能使某种生理功能保持相对稳定
E.
正反馈是某一生理过程逐步加强直至完成
【简答题】职业病与工作有关疾病的特点及区别?
【简答题】They put beautiful flowers and plants in the entenrance _____________ .
【简答题】Write about the following topic: In order to learn a language well, we should learn about the country as well as the cultures and lifestyles of the people who speak it. To what extent do you agree or ...
【单选题】People read newspaper to ______.
A.
learn about whatever they want
B.
learn about the most important news
C.
get some information (信息)
【单选题】The flowers were put on the table for ( ).
A.
ornament
B.
orenament
C.
ornamant
D.
ornement
【单选题】关于反馈作用的叙述错误的是
A.
是保证调节精确的重要机制
B.
反馈分为负反馈和正反馈
C.
负反馈能使某种生理功能保持相对稳定
D.
正反馈在机体功能调节中表现较为突出
E.
血糖浓度调节属于负反馈
【单选题】What happened to the flowers which were put in a laboratory in constant darkness?
A.
They didn't open at all.
B.
They opened as if they were in a normal garden.
C.
They have circadian cycles of activity.
D.
They died without knowing the time of day.
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