机车牵引特性的控制保证机车牵引时,在各挡转速下,维持主发电机的()。
参考答案:恒功
If you get the flu, you should ______________ for a few days.[ ]
A. watch TV
B. stay in bed
C. drink cola
—Happy Teachers’ Day! Here are some flowers for you.
— beautiful flowers they are! Thank you!
A.How
B.How a
C.What
D.What a