单项选择题
In an electro-hydraulic steering system, under movement is maintained in close synchronization with the steering wheel position by means of the （）.
A.trick-wheel B.follow-up control C.six-way valve D.Rapson slide
单项选择题 The internal force of a material, which tends to resist deformation when subjected to external forces, is known as （）.
单项选择题 An increase in rotor clearances in a rotary pump will （）.
单项选择题 Sweating of the refrigeration system compressor crankcase is caused by （）.
