二、名目匯率(nominalexchangerate)、實質匯率(realexchangerate)與實質有效匯率(realeffectiveexchangerate)三者之內容分別為何?上述三者, 何者可作為判斷一國貨幣價值是否被高估(overestimated)或低估 (underestimated)之參考?請說明之。(25分)