单项选择题
A.the crosshead
B.the journals of the crosshead
C.the crosshead shoes
D.the guides
单项选择题 The lower end of each piston rod is reduced in diameter to fit a bore in （）, this being secured to the piston rod by a nut.
单项选择题 The lower end of each piston rod is reduced in diameter to fit a bore in the cross-head, this being secured to the piston rod by （）.
单项选择题 The lower end of each piston rod is reduced in diameter to fit a bore in the （）, this being secured to the piston rod by a nut.