皮皮学，免费搜题
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搜题
【单选题】
用PWM控制直流电动机时，电枢绕组两端的电压平均值为UO=αUS，α为占空比。根据直流电机电压调速原理，可知电机转速与占空比成（ ）关系。A.
反比
B.
正比
C.
曲线
D.
不确定
拍照语音搜题，微信中搜索"皮皮学"使用
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皮皮学刷刷变学霸
举一反三
【单选题】This coat is _______ in the shop. [ ]
A.
expensive
B.
the most expensive
C.
more expensive
D.
most expensive
【单选题】Who most likely is the man?
A.
A doctor.
B.
A nurse.
C.
A flight attendant.
D.
A technical assistant.
【简答题】v. 登场,扮演
【简答题】Where does this conversation most probably take place? [A] In a shop. [B] At a hotel. [C] In a travel agency
【单选题】_______ wear white uniforms and help doctors in hospital.
A.
Bank clerk
B.
Doctors
C.
Nurses
D.
shop assistant
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