多轴飞行器使用的电调通常被划分为（）
A.有刷电调和无刷电调
B.直流电调和交流电调
C.有极电调和无极电调
参考答案：A
高铁血红蛋白还原试验正常人还原率为（）
A.10%
B.25%
C.45%
D.60%
E.75%以上
— I think students should have mobile phones to call their parents.
—_____. They often use them to play games instead.
A．I hope so
B．I don't agree
C．No problem
D．Good idea
