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
单项选择题 What is the meaning of “short hauls”?（）
单项选择题 Loss and damage ration for motor are lower than any other modes. Is it correct?（）
单项选择题 The international trade needs the（） to fulfill it’s transaction.
