问答题 假设世界上每一个人都为利息收入和因汇率改变而产生的资本收益支付τ/%的税，这项税收会对利率平价条件的分析产生什么影响?如果此项税收只针对利息收入，而不适用于资本利得，即不对资本利得征税，这时的情况又会怎样?
   Imagine that everyone in the world pays a tax of τ percent on interest earnings and on any capital gains due to exchange rate changes．How would such a tax alter the analysis of the interest parity condition? How does the answer change if the tax applies to interest earnings but not to capital gains，which are untaxed?