What is the best explanation to the underline phrase "to secure the smooth withdrawal of ships"？
A. To withdraw a ship mid make it in a safe condition
B. To secure the life of a ship and recycle it
C. To break a wreck
D. To finish the service of a ship and break it without other problems
在图19—8中，均衡的价格水平是________，同时均衡实际GDP是________万亿。
A. 110；11
B. 110；13
C. 100；12
D. 90；11
E. 90；13
Crankcase explosions in propulsion diesel engines result from
A. the splashing of lubrication oil by the crankshaft
B. the dilution of crankcase oil with particles of combustion
C. broken fuel lines spraying oil on the crankcase
D. the ignition of unburned fuel and air in the crankcase
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