单项选择题
An axial轴向 piston pump differs from a radial piston pump as the pistons of an axial piston pump are positioned （）.
A.radially from the shaft B.parallel to each other and to the shaft C.parallel to each other but at a right angle to the shaft D.at an angle to each other and to the shaft
单项选择题 The usual number of single-acting pistons used in a variable stroke axial-piston pump is （）.
单项选择题 The heat identified by only a change in temperature is known as （）.
单项选择题 The static suction lift of a pump is the difference in elevation between the （）.
