关税同盟

例句：

1. 1. The European Union is a free trade alliance among its member countries.
   欧盟是其成员国之间的自由贸易联盟。
2. 2. China and Japan have signed a free trade agreement to reduce tariffs on their goods.
   中国和日本签署了一项自由贸易协定，以降低它们商品的关税。
3. 3. The tariff union between the United States and Canada has been an important factor in their economic growth.
   美国和加拿大之间的关税同盟一直是它们经济增长的重要因素。