同步电动机启动时要将同步电动机的定子绕组通入()。
A.交流电压
B.三相交流电流
C.直流电流
D.脉动电流
参考答案:B
句型转换。
1. Where is Tim from? (改为同义句)
Where ______ Tim ______ from?
2. My pen friends come from Canada. (改为否定句)
My pen friends ______ ______ ______ Canada.
3. They come from the USA. (改为一般疑问句)
______ they ______ ______ the USA?
4. Lucy and Lily are from Singapore. (对画线部分提问)
______ ______ Lucy and Lily ______?
5. Eric lives in America. (对画线部分提问)
______ ______ Eric ______?
增液通下法主治()证。