单项选择题 In an oil cooler circulated by sea water, the oil is at a larger pressure, the result being that any leak in the cooler will mean a loss of （）.

单项选择题 In a four-stroke engine the camshaft rotates at （）.

单项选择题 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.