how many businessmen travel by air?

四. 段落翻译All around the world， large cities have the same problem：air pollution．Mexico City has very bad air．The air there is dirty and very unhealthy．Cars are one reason for the dirty air．Many Mexicans own their own cars and drive in the city．The factories in the area also cause air pollution．It is not easy to clean up the air in large cities．The government has to make new laws．

智慧职教: How many businessmen travel by air?

In the tower, there are many air traffic controllers helping take-off and landing of the _________. A:

One of the main reasons for air pollution is that many cars _______ smoke into the atmosphere.

The disadvantage of district ventilation is that there are many return air shafts and ventilation equipment.

Many trees _______ on the streets every years. So the air is very fresh now.

List as many useful sentences ralated to air ticket booking as you can.

In air cargo transportation， an air waybill has many functions， it can serve as an evidence of（ ）。 A: contract of carriage B: carrier C: receipt of goods D: shipper

中国大学MOOC: The air there is____, so many people from the city go there on weekends.