For example

At globalization ages, export of the main function lie in well comparison advantage of developing each economy, Yang long avoid short, the mutual communication has have no, common development.
For example, China produces of the clothing is of good quality but inexpensive, while Southeast Asia produce of fruits quality goods at reasonable price, China can have the clothing export of competitive advantage and change the fruits of returning Southeast Asia.Even if both parties produce of clothing and fruits total amount didn,t increase, but because the existence exchanges,the whole welfare of both parties consumer raised.
Be showed from this, export of purpose for changing to return to the product kimono that there is comparison advantage in other nations duty, then improve native people is welfare.If export is bigger than import, meeting backlog trade surplus and foreign exchange storage.