Lev1 关于Non-current liabilities的一个问题 求教！ better, example, because, interest, increase

Muddahudda

level1 book3 财务分析的notes p262 non-current liabilities中有段话实在没理解  求教：
"For analysis, the market value of a firm's debt may be more appropriate than its book value. For example, a firm that issued a bond when interest rates were low is relatively better off when interest rates increase. This is because the firm could repurchase the bond at its now-lower market value."

这里标红的两处interest rates是不是都是指市场利率（即实际利率）？如果是的话 市场利率既然增长了 market value不是应该也增长么？怎么会是now-lower?希望有大牛能帮我解释一下这句话 多谢了！

NakedPuts2011

这个interest rate 就是discount rate, 就像是你在算present value 时用的r.
Book value of the bond was the present value of the future payments at the issuance. The firm issues the bond when the interest rate is low, the Book value is high (because you are discounting the future cash flows at a lower interest rate); when the interest rate increases, the market value of the bond is lower ( discount at higher interest rate). If the firm buyback the bond now, the firm pays the market value of the bond, which is lower than the book value. (所以开头那句说The market value of the bond is more appropriate to use in analysis.)
呃，我不知道这个市场利率是什么，r就是你在用计算器算bond present value的时候输入的I/Y嘛~
没给别人解答过问题，我可能说得太啰嗦了。。。你感觉一下我主要的意思吧。。。
（PS：俺也是考生，不是专业的）