Lightning is caused by clouds（)electricity.

A . too much superheat B . insufficient superheat C . suction pressure too low D . excessive refrigerant returning to the compressor

A . pronounced local heating B . wind being pushed up a mountain C . a warm air mass rising over a cold air mass D . an increased lapse rate caused by advection of warm surface air

A . changes in the earth's magnetic field B . nearby magnetic land masses or mineral deposits C . magnetic influence inherent to that particular vessel D . the magnetic lines of force not coinciding with the lines of longitude

A . contamination B . oxidation C . tainting D . vaporizatio

A . operation of electrical equipment and generators on board ship B . the earth's magnetic field affecting the ship's hard iron during construction C . the horizontal component of the earth's magnetic field acting on the horizontal soft iron D . the vertical component of the earth's magnetic field acting on the vertical soft iro

A . vessel's geographic position B . vessel's heading C . earth's magnetic field D . influence of the magnetic materials of the vessel

A . a stuck solenoid valve B . a shortage of refrigerant C . too much oil in circulation D . too much superheat

A . density differences of the water B . rotation of the earth C . direction of primary circulation of air D . all of the above

A . Worn gears in the compass housing B . Magnetism from the earth's magnetic field C . Magnetism within the vessel D . Lack of oil in the compass bearing

A . low water in the expansion tank B . improperly seated valves C . low fuel oil pressure D . worn or broken cylinder liner sealing ring

A . low pressure area B . high pressure area C . area of calm air D . cold front overtaking a warm front

A . forest fires B . smoke from industrial areas C . dust or sand storms D . water droplets with the relative humidity more than 95%

A . the rotation of the earth on its axis B . convection currents caused by differences in radiant heating between equatorial and polar regions C . mountain ranges D . All of the above

A . the solid impurities of large particle B . the solid impurities of fine particle C . the water content D . both water and solid impuritie

A . the time of day B . the seasons C . geography D . All of the above

A．idiolect B．regional dialect C．sociolect D．diglossia

A．idiolect B．regional dialect C．sociolect D．diglossia