电气设备（electrical equipment）

Which statement concerning reserve sources of energy for GMDSS is FALSE ________．

A.While the ship is at sea，there must be available at all times a supply of electrical energy sufficient to operate the radio installations and to charge any batteries used as part of a reserve source of energy

B.Both the VHF and MF/HF installations must be simultaneously supplied

C.A means of ensuring a continuous supply of electrical power must be provided to all GMDSS equipment that could be affected by an interruption in power

D.If a UPS or equivalent is used to supply power to the ship's GPS receiver or other source of positional information，a means must be provided to ensure the continuous supply of the information in the event of a failure to the ship's main or emergency source of power

Permanent magnetism is caused by ______.

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 iron

One disadvantage of using regular dry chemical（sodium bicarbonate）in firefighting is that ______．

A.It can break down under high heat and emit noxious fumes

B.It will decompose under prolonged storage and lose its effectiveness

C.Fire has been known to flash back over the surface of an oil fire

D.It is ineffective in fighting fires in high-voltage electrical equipment

Loran-C is which type of system ________．

A.Reflected electron

B.Electrical radiation

C.Quarterpoint electrical navigation

D.Hyperbolic radio navigation