不属于水表使用维护内容的是（）。
A.检查灵敏度指针是否转动
B.检查接头渗漏
C.水表检定
D.水表室内阀门功能检查
参考答案：C
Most of the teaching equipment presented by the Hope Project, as well as the books, made
good use of in the village school.[ ]
A. has
B. have
C. have been
D. has been
雷达接收机输出的信号是（）
A、射频回波信号
B、本振信号
C、中频信号
D、视频回波信号
