假设一些外国开始通过制定投资税来补贴投资。 a.作为世界利率函数的世界投资需求会发生什么变动? b.世界利率会发生什么变动? c.我们小型开放经济的投资会发生什么变动? d.我们的贸易余额会发生什么变动? e.我们的实际汇率会发生什么变动? Suppose that some foreign countries begin to subsidize investment by instituting an investment tax credit. a.What happens to world investment demand as a function of the world interest rate? b.What happens to the world interest rate? c.What happens to investment in our small open economy? d.What happens to our trade balance? e.What happens to our real exchange rate?