改进题：This concept says that a nation has a comparative advantage in an item if it can produce it more efficiently than alternative products.

译文：比较优势是指假如一个国家生产某种产品的效率高比生产其他产品。

改进题：This concept says that a nation has a comparative advantage in an item if it can produce it more efficiently than alternative products.

译文：比较优势是指假如一个国家生产某种产品的效率高比生产其他产品。

改进的译文：比较优势是指假如一个国家生产某种产品比生产其他产品的效率高，那么它就具有生产该产品的比较优势。