注汽锅炉上的柱塞泵控制电路由()组成。
(A)自动空气开关
(B)交流接触器
(C)热继电器
(D)A、B、C均正确
参考答案:D
There are two ways from here to the station. You can go ________ way. [ ]
A. both
B. all
C. either
D. every
The number of students in a foreign languages class ______ usually limited to no more than thirty.
A.have
B.are
C.is
D.were