单项选择题
A.advanced
B.retarded
C.kept constant
D.none of the above
单项选择题 With the shell and cap assembled as for running, a check must be made that the clearance between the cap and the housing ().
单项选择题 With the crank in position in the engine, some measurements can be taken by a special bridge gauge and ().
单项选择题 With four-stroke engines, it takes four revolutions of the crank shaft to make () power stroke(s).