The security function of the fca is diminishing and the area should be well - utilised 边界禁区的保安功能正逐步减低，应充分利用该区的土地。
2.
Series installations are recommended where very high supply pressure must be reduced to a very low downstream pressure . reducing the pressure in stages eliminates whistling and noise 如果很高的供应压力必须降低到很低的下游压力，则建议采用串联安装方式。逐步减低的压力避免出现啸声和噪音。
