单项选择题
The cast iron guide-ways for （） are attached to the top section and seal off the crankcase.
A.the connecting rod B.the cross-head C.the piston rod D.the air box
单项选择题 The cast iron（）for the cross-head are attached to the top section and seal off the crankcase.
单项选择题 The carbon deposits on the piston crown and in the ring grooves （）.
单项选择题 The cap and new shell are tightened up and then removed and the thickness of the wire measured by （）.
