给你些hints吧
agree：1 can improve the competition among the world so that improve the productivity and accelerate the technolgy improvement.
2 free trade can break the monoply which would control the price and supply.and would meet the additional demand in the country.
3 every one around the world can buy the same price goods.
disagree:1 free trade would cause dumping if there is no tariff.tariff would influence the other countries home netwealth and would cause a deadweight loss.(based on international trade policy)
2 free trade can not protect the infant companies of the country.the country which depend on more imports will influence the country's balance of payment and account deficit.
以上是根据国际贸易和金融学的知识总结的.不知道能不能明白!