单项选择题
A.the cylinder B.the crankshaft C.the piston D.the cross-head
In each cylinder cover there are two or three holes for...
单项选择题In each cylinder cover there are two or three holes for （）
A.the exhaust valves B.the fuel valves C.indicator cocks D.the fuel pumps
In each cylinder cover is a large central opening for m...
单项选择题In each cylinder cover is a large central opening for mounting （）
A.the indicating cock B.the starting valve C.air inlet valve D.the exhaust valve
In an ordinary four-stroke engine the exhaust valves op...
单项选择题In an ordinary four-stroke engine the exhaust valves open （）
A.after TDC B.before TDC C.after BDC D.before BDC
