利用延时器产生回声效果,一般延时器的延时时问设定为()。
A、5m一35ms
B、35ms一50m
C、50ms以上
参考答案:C
—Can you imagine Mike across the Atlantic within a single day?
—We all imagine him a brave and determined person. [ ]
A. to sail; to be
B. sailing; being
C. to sail; being
D. sailing; to be
潜油电泵测压阀安装在单向阀下方。