单项选择题
A.the cylinder weight
B.the cylinder bore
C.the cylinder length
D.the cylinder cover
单项选择题 The main factor determining the output of each cylinder is the cylinder （）.
单项选择题 The main bearings are provided with thin-walled （）, lined with a copper-lead alloy.
单项选择题 The main bearing shells often have a thin （） of lead or indium to provide a layer giving protection against corrosion.