单项选择题
A.through bolts B.turbo-chargers C.bed plates D.columns
Smaller engines can be made more rigid than large ones ...
单项选择题Smaller engines can be made more rigid than large ones and may not have （）.
A.through bolts B.dividing walls C.sloping surfaces D.relative angles
A.connecting rods B.crankshaft C.crankcase D.through bolts
Since the burning or combustion takes place within the ...
单项选择题Since the burning or combustion takes place within the engine itself, the engine is known as （）.
A.a fire -tube boiler B.an internal combustion engine C.an external combustion engine D.an internal combustion generator
