单项选择题
A. cost reduce B. cost increase C. effective D. efficient
What kind of products do the air carriers deliver? （）A....
单项选择题What kind of products do the air carriers deliver? （）
A. The high value B. Low density or weight C. A and B D. To add cost
（）is the disadvantage for air transportation?A. Quick b...
单项选择题（）is the disadvantage for air transportation?
A. Quick but not safe B. Less frequency C. It can’t lift heavy goods D. the highest cost in all transport modes
What is the meaning of “short hauls”? （）A. Near wayB. T...
单项选择题What is the meaning of “short hauls”? （）
A. Near way B. The distance is not long C. Direct line D. Short road
