所以答案就是得到一个long bond？如何得到无风险套利

NO.PZ2018062007000085问题如下 Unr put–call–forwarparity, whiof the following transactions is risk free? A.Short call, long put, long forwarcontract, long risk- free bonB.Long call, short put, long forwarcontract, short risk- free bonC.Long call, long put, short forwarcontract, short risk- free bon A is correct. Purchasing a long forwarcontraana risk- free boncreates a synthetic asset. Combining a long synthetic asset, a long put, ana short call is risk free because its payoffs proa known cash flow of the value of the exercise price. 中文解析这道题考察的是put-call parity的一个变形。我们知道S是一个不确定的现货价格，那么假设持有S同时short forwarcontract，就可以得到一个无风险收益，可以等效为一个risk-free bon也就是S + short forwarcontra= long risk-free bon等式两边变换一下可以得到S = -short forwarcontra+ long risk-free bon= long forwarcontra+ long risk-free bon再把这个等式带入到P + S = C + K，得到P + long forwarcontra+ long risk-free bon= C + K，K是无风险债券 Risk free bonK = P + long forwarcontra+ long risk-free bon- C，这样就构造了一个无风险组合，A对。 为什么s价格不确定要short forwarcontract而不是long forwarcontract？

NO.PZ2018062007000085问题如下 Unr put–call–forwarparity, whiof the following transactions is risk free? A.Short call, long put, long forwarcontract, long risk- free bonB.Long call, short put, long forwarcontract, short risk- free bonC.Long call, long put, short forwarcontract, short risk- free bon A is correct. Purchasing a long forwarcontraana risk- free boncreates a synthetic asset. Combining a long synthetic asset, a long put, ana short call is risk free because its payoffs proa known cash flow of the value of the exercise price. 中文解析这道题考察的是put-call parity的一个变形。我们知道S是一个不确定的现货价格，那么假设持有S同时short forwarcontract，就可以得到一个无风险收益，可以等效为一个risk-free bon也就是S + short forwarcontra= long risk-free bon等式两边变换一下可以得到S = -short forwarcontra+ long risk-free bon= long forwarcontra+ long risk-free bon再把这个等式带入到P + S = C + K，得到P + long forwarcontra+ long risk-free bon= C + K，K是无风险债券 Risk free bonK = P + long forwarcontra+ long risk-free bon- C，这样就构造了一个无风险组合，A对。 请问这道题怎么区分 rf 和 K呢？ 都是 risk free bon

NO.PZ2018062007000085 问题如下 Unr put–call–forwarparity, whiof the following transactions is risk free? A.Short call, long put, long forwarcontract, long risk- free bon B.Long call, short put, long forwarcontract, short risk- free bon C.Long call, long put, short forwarcontract, short risk- free bon A is correct. Purchasing a long forwarcontraana risk- free boncreates a synthetic asset. Combining a long synthetic asset, a long put, ana short call is risk free because its payoffs proa known cash flow of the value of the exercise price. 中文解析这道题考察的是put-call parity的一个变形。我们知道S是一个不确定的现货价格，那么假设持有S同时short forwarcontract，就可以得到一个无风险收益，可以等效为一个risk-free bon也就是S + short forwarcontra= long risk-free bon等式两边变换一下可以得到S = -short forwarcontra+ long risk-free bon= long forwarcontra+ long risk-free bon再把这个等式带入到P + S = C + K，得到P + long forwarcontra+ long risk-free bon= C + K，K是无风险债券 Risk free bonK = P + long forwarcontra+ long risk-free bon- C，这样就构造了一个无风险组合，A对。 是如何得出求的是K呢

NO.PZ2018062007000085 问题如下 Unr put–call–forwarparity, whiof the following transactions is risk free? A.Short call, long put, long forwarcontract, long risk- free bon B.Long call, short put, long forwarcontract, short risk- free bon C.Long call, long put, short forwarcontract, short risk- free bon A is correct. Purchasing a long forwarcontraana risk- free boncreates a synthetic asset. Combining a long synthetic asset, a long put, ana short call is risk free because its payoffs proa known cash flow of the value of the exercise price. 中文解析这道题考察的是put-call parity的一个变形。我们知道S是一个不确定的现货价格，那么假设持有S同时short forwarcontract，就可以得到一个无风险收益，可以等效为一个risk-free bon也就是S + short forwarcontra= long risk-free bon等式两边变换一下可以得到S = -short forwarcontra+ long risk-free bon= long forwarcontra+ long risk-free bon再把这个等式带入到P + S = C + K，得到P + long forwarcontra+ long risk-free bon= C + K，K是无风险债券 Risk free bonK = P + long forwarcontra+ long risk-free bon- C，这样就构造了一个无风险组合，A对。 P + long forwarcontra+ long risk-free bon= C + K这里假如我把long risk-free bon到等式一边，其他所有东西移动到另一边，这也是构建了一个新的risk-free的组合吗？虽然结论和A的区别就是整体加了一个负号？

NO.PZ2018062007000085问题如下 Unr put–call–forwarparity, whiof the following transactions is risk free? A.Short call, long put, long forwarcontract, long risk- free bonB.Long call, short put, long forwarcontract, short risk- free bonC.Long call, long put, short forwarcontract, short risk- free bon A is correct. Purchasing a long forwarcontraana risk- free boncreates a synthetic asset. Combining a long synthetic asset, a long put, ana short call is risk free because its payoffs proa known cash flow of the value of the exercise price. 中文解析这道题考察的是put-call parity的一个变形。我们知道S是一个不确定的现货价格，那么假设持有S同时short forwarcontract，就可以得到一个无风险收益，可以等效为一个risk-free bon也就是S + short forwarcontra= long risk-free bon等式两边变换一下可以得到S = -short forwarcontra+ long risk-free bon= long forwarcontra+ long risk-free bon再把这个等式带入到P + S = C + K，得到P + long forwarcontra+ long risk-free bon= C + K，K是无风险债券 Risk free bonK = P + long forwarcontra+ long risk-free bon- C，这样就构造了一个无风险组合，A对。 题面问的risk free，我首先反应为公式c+K=p+F+rf 所以变形以后三个答案都不匹配。我想问的是若不从答案出发反推问题，这个问法是不是也可以理解为forwar现的rf