工作火花
参考答案：
电气设备正常工作时或正常操作时出现的火花。
Your shoes ______ easily but they ______ well.[ ]
A. wear; haven't worn
B. are worn; haven't worn
C. wear; haven't been worn
D. are worn; haven't been worn
弹簧管压力表主要由（）管、传动机构、指示机构、表壳等四大部分组成。
A、弹簧
B、V型
C、O型
D、干簧
