单项选择题 The viscosity regulator controls （） in order to provide oil at the correct viscosity for combustion.

单项选择题 The vessel is out of harbor and in “Full Ahead”We are going to run fuel oil instead of （） and open the fuel oil heater steam valve.

单项选择题 The two-stroke cycle begins with the piston coming up from the bottom of its stroke, with scavenge ports in the sides of the cylinder being （）.