It can be inferred from the passage that ______.

单项选择题The author draws the regulated tariff rates to show that the three countries ______.

单项选择题The economic performance of these three countries may improve because ______.

单项选择题It can be learned from the passage that the new customs union ______.

单项选择题What conclusion can be drawn from the passage

单项选择题The agreement the three presidents assigned on Tuesday implies that ______.