问题：
[单选] In a four-stroke engines the camshaft rotates at （）.
half the engine rotational speed。twice the engine rotational speed。the engine rotational speed。four times the engine rotational speed。
问题：
[单选] In a general oil cooler circulated by sea water, the oil is at a higher pressure, the result being that any leak in the cooler will mean a loss of （）.
oil。sea water。air。fresh water。
问题：
[单选] In a purifier changing to a gravity disc with larger hole diameter will move the interface towards the （）.
bowl periphery。bowl center。upper surface。lower surface。
问题：
[单选] In a purifier, the interface between the liquid seal and the oil should be positioned as close as possible to （）.
the outlet of oil。the outlet of water。the bowl periphery。the center of bowl。
问题：
[单选] In a typical fuel oil system, the oil is stored in tanks in the double bottom from which it is pumped to （） and heated.
a service tank。a collecting tank。a sump。a settling tank。
问题：
[单选] In a typical fuel system, the oil is stored in （） in the double bottom.
setting tanks。service tanks。tanks。drain tank。
问题：
[单选] In addition to lubricating, cylinder oil assists in forming a gas seal and contains （） which clean the cylinder liner.
additives。water。grease。acid solutio。
问题：
[单选] In an engine with a pot-shaped piston, some lubricating oil from the main bearing will pass along a drilled passage in the crankshaft to the bottom end bearing and then up a connection rod to the （）.
crosshead。crankpin。crank journal。gudgeon pi。
问题：
[单选] In an engine with a pot-shaped piston, some lubricating oil from the main bearing will pass along a （） in the crankshaft to the bottom end bearing andthen up a connection rod to the gudgeon pin.
telescopic pipes。large bore。drilled passage。tied rod。
问题：
[单选] In an engine with air inlet valve and exhaust valve on its cylinder heads the fresh air will enter into the cylinder （） and the gases exhaust （）, there being an adequate overlap between the inlet opening and the exhaust closing.
downwards；upwards。upwards；downwards。downwards；downwards。upwards；upward。
