Portable carbon dioxide fire extinguishers should be sent ashore to be recharged

A．when the remaining charge volume is less than 90 percent of the required volume

B．at each inspection for certification

C．at each annual inspection

D．when the weight loss exceeds 10% of weight of charge

[单选题]Carbon is an element， while carbon dioxide is a( )A.materialB.substanceC.or

[单选题]Carbon is( )， while carbon dioxide is a compound.A.a materialB.a substanceC

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

[单选题]F．ire dampers prevent the fire spreading through the process ofA．convectionB．conductionC．radiationD．direct contact

[名词解释] 英译中：Portable Data Terminal

[名词解释] 移动式设备（portable equipment）

[单选题]One of the disadvantages of using carbon dioxide to extinguish a fire in an enclosed space isA．the 'snow' which is sometimes discharged along with the gas is toxicB．prolonged exposure to high concentrations of CO2 gas causes suffocationC．rapid diss

[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

[名词解释] 英译中：Portable data terminal(PDT)

[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