为自己加油

Solenoid valves shall be shown with a notation indicating whether the valve is spring-loaded to the open or closed position.

A.使用符号代表电磁活门，显示该活门是否是弹簧加载到开位或关位。
B.应针对电磁活门标明注意事项，说明该活门应该弹簧加载到开位还是关位。
C.电磁活门应标有符号，表明该活门是弹簧加载到开位还是关位。