预埋标高基准点主要用于( )设备的安装。
A．独立生产
B．自动生产线
C．多机生产
D．连续生产线
参考答案：D
After a knock at the door, the child heard his mother’s voice ____ him. [ ]
A. calling
B. called
C. being called
D. to call
国家在必要时设立特别行政区，在特别行政区内实行的制度由( )规定。
A．自治条例
B．单行条例
C．法律
D．宪法
