下列()是管道系统防超压的措施。
A、采用减压稳压消火栓
B、选用流量-扬程曲线平缓的消防水泵
C、设置安全阀或其他泄压装置
D、设置消声止回阀
参考答案:A, B, C
The city ________ against the terrible possibility of such things happening again.
A.makes its breath
B.takes its breath
C.holds its breath
D.lets its breath
工程中常见的周期信号其谐波的幅值随谐波的频率增加而()
A.不变
B.减小
C.增加
D.不确定