变换异步电动机( )极对数从而改变同步转速的调速方式成为变极调速。
A．电源
B．绕组
C．接线端子
D．电枢
参考答案：B
自动取款机可提供（）项交易。
A.存款
B.取款
C.查询余额
D.转账
E.改密
An inflatable liferaft can be launched by（）.
A.the float-free method ONLY
B.breaking the weak link on the painter
C.throwing the entire container overboard and then pulling on the operating cord to inflate the raft
D.removing the securing straps
