Because countries often have differing political and economic systems, agreements are needed to protect those invested in trade.

Because countries often have differing political and economic systems, agreements are needed to protect those invested in trade.

由于各国往往有着不同的政治和经济体系，因此需要达成协议来保护那些投资于贸易的国家。

-- David Suzuki 大卫铃木