这句话摘自,《国际贸易实务》英文版,全文是这样说的, For one thing, countries trade becasue there is a cost advantage from production efficiency as demonstrated in the principle of comparative advantage. Further, the prices fall because trade allows firms to produce further down along the erage cost curve adn that means a lower per unit cost of production. This implies that each product is being produced more efficiently. In addition, competition in the world market remains strong and constant and it forces profit to[收起]