单项选择题
An internal bypass is provided on some hydraulic system suction strainers to help reduce the possibility of （）.
A.aeration of the oil B.contamination of the oil C.pump cavitation D.spongy actuator movements
单项选择题 A grease gun is generally used to lubricate a （）.
单项选择题 Thermostatic expansion valves can be adjusted for （）.
单项选择题 The amount of fluid friction or internal friction inherent in a mineral lubricating oil is reflected as a measure of its （）.
