单项选择题 The bedplate must be rigid enough to support the weight of the rest of the engine, and maintain the crankshaft, which sits in the bearing housings in the （）, in alignment.

单项选择题 Pressurized air enters the cylinder via the inlet ports and pushes the remaining exhaust gas from the cylinder in a process known as “（）”.

单项选择题 It is during （） that work energy is being put into the engine; during the other 3 strokes of the piston, the engine is having to do the work.