【简答题】题8.5.5图所示是并励电动机能耗制动的接线图。所谓能耗制动,就是在电动机停车时将它的电枢从电源断开而接到一个大小适当的电阻R上,励磁不变。试分析制动原理。
【单选题】【会社で、電話の相手の名前を尋ねる時に】 敬語の使い方が適切なのはどれでしょう?
【简答题】用 more than, no more than, not more than, no more ... than, not more ... than填空。 Mr .Li is ________ a professor; he isalso a famous scientist.
【单选题】Liu Li is _____ outgoing _____ her sister. [ ]
【简答题】求心形线,r=a(1+cosθ)的全长,其中a>0是常数.
【单选题】Li Lei is__________ more athletic than me. [ ]
【单选题】Uncle Ross has been a li b rarian for more than thirty years.
C.
for more than thirty years
【单选题】三相异步电动机采用( )时,能量消耗小,制动平稳。