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.

单项选择题 Which of the following operations aboard a tanker must be recorded in the Oil Record Book （）

单项选择题 The lowest temperature at which the vapor formed from a liquid ignites and continues to burn steadily in the presence of an ignition source is called the （）