TB为什么要说excess long-term Treasury bond (TB) is realized as 2.0%，这个excess不能理解为风险溢价部分吗？

请问计算债券价格什么时候可以用计算器

Prepayment risk is associated with declining interest rates on a pool of residential mortgages. The percentage of the pool that is paying on time in relation to those who are delaying payments is known as the delinquency measure. The PSA prepayment benchmark assumes that the monthly prepayment rate for a mortgage pool increases as it ages. Severity, default, and delinquency measures are all important credit risk measures for a pool of mortgages 老师可以帮我翻译一下吗，这个地方上课在哪讲过啊，我记得老师就在住房抵押贷款的地方简单提过一下，为什么提前偿付会有风险呢，提前还钱不是挺好吗

B选项是什么东西啊

老师，A选项能具体讲一下吗

66 为什么这样做？？ 为什么要折现 看不懂

Q64 为什么用2月9的libor

c选项不是很明白，麻烦老师再讲一下

我是用条件概率的公式，算出来每一个值加总的。虽然也对，但是3X7的做法太快了！请解释一下谢谢。

老师，这个题，我理解独立情况下的公式，但是3和7是打哪里来的？？？