没懂这个公式中的r 到底为啥是负的？是r 还是q？

NO.PZ2016082404000026问题如下 The vinyielof asset is 10% per annum. Whis the lta of a long forwarcontraon the asset with six months to maturity?   0.95   1.00   1.05   Cannot termine without aitioninformation ANSWER: AThe lta of a long forwarcontrais e−r∗τ=e−0.10×0.5=0.95.e^{-r\ast\tau}=e^{-0.10\times0.5}=0.95.e−r∗τ=e−0.10×0.5=0.95. 这个没有看出来为什么lt是e 的分红率乘以时间，不应该是无风险报酬率减分红吗

NO.PZ2016082404000026问题如下 The vinyielof asset is 10% per annum. Whis the lta of a long forwarcontraon the asset with six months to maturity?   0.95   1.00   1.05   Cannot termine without aitioninformation ANSWER: AThe lta of a long forwarcontrais e−r∗τ=e−0.10×0.5=0.95.e^{-r\ast\tau}=e^{-0.10\times0.5}=0.95.e−r∗τ=e−0.10×0.5=0.95. 这是哪的知识点？？？

NO.PZ2016082404000026 问题如下 The vinyielof asset is 10% per annum. Whis the lta of a long forwarcontraon the asset with six months to maturity?   0.95   1.00   1.05   Cannot termine without aitioninformation ANSWER: AThe lta of a long forwarcontrais e−r∗τ=e−0.10×0.5=0.95.e^{-r\ast\tau}=e^{-0.10\times0.5}=0.95.e−r∗τ=e−0.10×0.5=0.95. 老师，讲义中lta of a long forwaris always 1,指的是基础资产不分红的情况是吗？如果基础资产有分红，lta of a long forwar就是 eq×T1​ ，对么？谢谢。

NO.PZ2016082404000026 The vinyielof asset is 10% per annum. Whis the lta of a long forwarcontraon the asset with six months to maturity?   0.95   1.00   1.05   Cannot termine without aitioninformation ANSWER: A The lta of a long forwarcontrais er∗τ=e−0.10×0.5=0.95.e^{r\ast\tau}=e^{-0.10\times0.5}=0.95.er∗τ=e−0.10×0.5=0.95. The lta of a long forwarcontrais  er∗τ=e−0.10×0.5=0.95. 请问公式上面应该是E q*t，还是E -q*t？ 领完，long和short是否公式一样？