One of the disadvantages of using carbon dioxide to extinguish a fire in an enclosed space is

A．the 'snow' which is sometimes discharged along with the gas is toxic

B．prolonged exposure to high concentrations of CO2 gas causes suffocation

C．rapid dissipation of the CO2 vapor

D．the CO2 gas is lighter than air and a large amount is required to extinguish a fire near the deck

[单选题]One of the disadvantages of traveling as an air courier is that he_____.A． cannot decide when and where to travelB． cannot take any luggage with himC． has to wear two pairs of jeansD． saves little money from the travel

[单选题]One limitation as to why using the average duration of the bonds in a portf

[单选题]An analyst wants to compare the cash flows of two U.S. companies, one that

[单选题]There are advantages and disadvantages to 21 Asian and Western educational method. For example, one advantage 22 the education in Japan is that students there learn much more math and science 23 American students. They also study more hours each day

[单选题]The disadvantages of rail compared with motor carrier are（）A . CostB . SpeedC . Lost and damage ratiosD . Transit time and frequency of service

[单选题]The carbon deposits on the piston crown and in the ring grooves （）.A . should be scrapedB . should be derustedC . should be drilled outD . to be brushed off

[单选题]Portable carbon dioxide fire extinguishers should be sent ashore to be rechargedA．when the remaining charge volume is less than 90 percent of the required volumeB．at each inspection for certificationC．at each annual inspectionD．when the weight loss e

[名词解释] 异头碳（anomeric carbon）

[单选题]In order to cut down on the carbon emission，more people choose to travel______.A．by electric car，bicycle or planeB．by private car，bicycle or busC．by bus，electric car or planeD．by bicycle. bus or electric car

[单选题]As compared to carbon dioxide，dry chemical has which advantage?（）A . CleanerB . Effective on metal firesC . Greater rangeD . More cooling effect