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
单项选择题 what kind of products do the air carriers deliver? （）
单项选择题 What is the disadvantage for air transportation? （）
单项选择题 Loss and damage ration for motor are lower than any other modes. Is it correct?（）
