单项选择题
A.Separately B.In same level C.In the lower part D.Not mention here
How much is the percent of air transportation in all mo...
单项选择题How much is the percent of air transportation in all modes?（）
A.Less than 1% B.Lowest C.Lower D.Low
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.Shortest time to transport
What is the disadvantage for air transportation?（）A.Qui...
单项选择题What 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
