单项选择题
A.an electric grinder
B.a metal scraper
C.a reamer
D.a three-wing hone
单项选择题 Which of the following problems can cause an above normal air temperature to develop in the intake manifold of a turbocharged and after-cooled diesel engine?（）
单项选择题 Which of the following conditions can cause below normal air pressure in the intake manifold of a turbocharged diesel engine?（）
单项选择题 If sludge accumulates on the underside of a diesel engine piston, it will（）