单项选择题
What are transported mainly by water? （）
A. Raw materials B. Heavy, bulky and low value commodities C. Semi-processed D. Great amount goods
单项选择题 How many categories are there in water transport?（）
单项选择题 How many tons does the cargo 737 carry? （）
单项选择题 Where is the most air freight shipped in the passenger aircraft?（）
