在GMDSS中，DSC设备对SSB收发信机频率容限的要求是（）
A、±15HZ
B、±10HZ
C、±40HZ
D、±5HZ
参考答案：B
热凝塑料在常压下聚合时水温最后加热到
A．100℃
B．100.3℃
C．135℃
D．123.8℃
E．139.3℃
All but one _____ here just now. [ ]
A. is
B. was
C. has been
D. were
