This is the principle of comparative advantage and it has persuaded many countries to sign up to free-trade agreements, but unfortunately, it can take a long time for countries to trade their way to prosperity.

这就是比较优势原理，这说服了很多国家签署自由贸易协议，但很不幸，需要很长时间，才能让各国都通过贸易实现繁荣。