单项选择题
A.lead B.forged steel C.alloy steel D.aluminum alloy
Pistons may be made in （） in order to keep the weight d...
单项选择题Pistons may be made in （） in order to keep the weight down for balancing purposes at high speed.
A.cast iron B.forged steel C.stainless steel D.aluminum alloy
Piston No2 of main engine has been removed, and it will...
单项选择题Piston No2 of main engine has been removed, and it will be （） by noon tomorrow.
A.lifted B.reassembled C.dismounted D.disassembled
Persistent knocking in one cylinder of a diesel engine ...
单项选择题Persistent knocking in one cylinder of a diesel engine could be caused by（）.
A.a low load on that cylinder B.sluggish piston ring action C.excessive piston crown cooling D.excessive clearance of piston pin
