用检漏液或肥皂水检查管路各部分密封情况及燃气速断阀应无()。
A、损坏
B、脱水
C、失灵
D、渗漏
参考答案:D
I'm going to the beach I enjoy . [ ]
A. so; swiming
B. and; swims
C. or; to swim
D. because; swimming
自动频率控制电路是一个正反馈系统。