When welding or burning aboard a vessel, you must be certain that the space （）.

A . gives up large amount of heat B . gives off large amount of heat C . gives up large amount of steam D . gives off large amount of steam

A . facial respirator mask B . ear plugs C . rubberized boots D . fireman's outfit

A . relieves the officer of the watch B . relieves the Master of his duties C . is solely responsible for the safe navigation of the vessel D . is a specialist hired for his or her local navigational knowledge

A .  All "Add" channels require uniform power levels. B .  The flexibility of wavelengths per OADM is limited. C .  It is easier to balance "Pass-Through" and "Add" channels. D .  There is lower pass-through loss using multi-channel OADMs. E .  You can extract a single channel without dropping other channels.

A . a marine chemist B . the Officer in Charge，Marine Inspection C . the Master or person in charge of the ship D . the National Fire Protection Associatio

A . a fire -tube boiler B . an internal combustion engine C . an external combustion engine D . an internal combustion generator

A . Heat-resistant B . Rubber gloves C . PVC gloves D . Leather glove

A . using a rotary grinder with an installed shield B . letting go the anchor C . handling wire rope or natural fiber line D . painting with a spray gu

A . From Default Programs， modify the AutoPlay settings. B . From Default Programs， modify the default program settings. C . From Device Manager， modify the properties of the DVD drive. D . From System Configuration Utility， modify the Startup settings.

A . flush water over any burned area of the patient B . apply ointment to the burned areas on the patient C . get assistance to shut down electrical power in the area D . remove the patient from the vicinity of the live electrical equipment or wiring

A . gas freed B . inerted C . filled with water D . all of the above as necessary

A . are forbidden B . are allowed C . can be used D . are usually used

A．his trips there were too frequent B．their interest in his poems began to decrease C．they disapproved of his habits D．they could not catch up with his fast-paced life style

A．Future happiness is attractive. B．The man should retire early. C．Today's happiness is less important than tomorrow's. D．It doesn't make sense to work for the happiness of future.

A．apologise B．contribute C．disturb D．dispose of

Pain can take complete control of our body and mind, making it impossible to move and even to think. Yet we need pain. Without it, we would not know if we have hurt ourselves. It is our body's warning system________­­­­_47) Pain is the most common reason we go to a doctor. It is the most common reason we take medicines. Until recently, however, most doctors knew of only a few drugs that stopped some pains_________(48) But new knowledge about the process of pain is helping them to control pain better. Scientists have learned that the sense of pain is made up of both chemical and electrical signals_________(49) Scientists also have learned that the nervous system sends two different kinds of pain messages to the brain: one very fast, the ether slow. The first message is the warning signal. It moves at a speed of 30 meters a second. In less than a second, the brain understands that part of the body is hurt and how badly it is injured________(50) It tells us not to use the injured part until it heals. A．And others have painful attacks all the time. B．These signals travel from nerve cells in the injured area, up the spinal cord (脊髓) to the brain, and back down again. C．It tells us that we are injured and should do something about it. D．They knew little about the process of pain itself. E．The other message moves at a speed of only one meter a second. F． And they send the second, slower message of pain to the brain. 第 46 题 请选择（46）处的最佳答案．