[单选] A more sophisticated pressure reducing valve incorporates a pilot valve which controls the fluid above the valve operating piston in response to downstream pressureThe bold and italic word “which” means （）.

自定义三管塔模块价格按照（）来计价。 吨。 米。 立方米。 平方米。 为什么要在水产动物饲料中添加矿物质元素？ 物资采购项目包括哪些内容？申报审批是如何规定的？ The biggest problem you generally encounter while towing a single tow astern is（）. the catenary dragging on the bottom。 swamping of the tow。 the tow tending to dive。 yaw。 烟用物资采购遵循的原则有哪些？ A more sophisticated pressure reducing valve incorporates a pilot valve which controls the fluid above the valve operating piston in response to downstream pressureThe bold and italic word “which” means （）.