单项选择题
Flexible hose under pressure in a hydraulic system will （）.
A.tend to twist about its long axis B.expand in length and in diameter C.contract in length and expand in diameter D.flex at right angles to the applied pressure
单项选择题 An air compressor can be unloaded at start-up by （）.
单项选择题 Machinery driving fuel oil transfer and fuel oil service pumps must be fitted with a remote means of stopping the machinery from （）.
单项选择题 If an electric motor driven air compressor fails to start, it may be due to a （）.
