单项选择题 A(n) （） is a device which adds to the energy of a liquid or gas causing an increase in its pressure and a movement of the fluid.

单项选择题 Lubricating oil systems are fitted with a wide variety of strainers some of which can be cleaned in site while others have replaceable cartridgesThe bold and italic word “which” means （）.

单项选择题 In many installations basket strainers consist of a cylindrical container in which a perforated metal or wire basket is suspendedThe bold and italic word “which” means （）.