如果为阀门或控制建立符号或图案，这种类型的装置在整个手册中都要用它。使用的符号应在原理图 的图例块中显示和标识。
A.If a symbol or device is established for a valve or control, it shall be used for this type of unit throughout the manual. The symbols used should be shown and identified in legend a block on the schematic diagram. B.If a symbol or device has been set up to a valve or control, the equipment type will be referred, to as this symbol or device, throughout the manual. The legend block in the diagram displays or identifies symbols or device. C.If symbol or design is specified for a valve or control, this type of device is used throughout the section of the manual. The symbols used can be found and identified in the legend block cofOthe schematic, a正确答案A
