墨西哥和巴西各自的贸易伙伴不同。墨西哥主要与美国贸易,巴西与美国和欧盟的贸易量大致相当。墨
Mexico and Brazil have very different trading patterns. Mexico trades mainly with the United States,Brazil trades about equally with the United States and with the European Union; Mexico does much more trade relative to its GDP.Explain these differences using the gravity model,