单项选择题
What is the meaning “speed is not of primary importance”?（）
A.Speed is important B.Speed is not the most important C.Speed is mainly important D.Speed is first importan
单项选择题 What are transported mainly by water?（）
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?（）
