在某些情况下，相对供给和价格的变动之间可能没有联系。例如：如果生产要素在部门之间完全不可流动，生产可能性

边界就会成为直角形状，两种产品的产出也不取决于它们的相对价格。在这种情况下，贸易条件的改善是否会提高一国的福利水平？请画图进行分析。

In some economies relative supply may be unresponsive to changes in prices．For example，if factors of：production were completely immobile between sectors，the production possibility frontier would be right-angled，and output of the two goods would not depend on their relative prices．Is it still true in this case that a rise in the terms of trade increases welfare？ Analyze graphically．