问题如下图：
选项：
A. 
B. 
C. 
D. 
解释：
请问如何理解第三个maturity那里呢？
品职答疑小助手雍 · 2019年09月08日
同学你好，就根据解析里第一行那个公式啊，t越小，那个指数项就越大，B就越大。iii说t越大，那就错了。
陈晓昭 · 2019年10月07日
如果是risky bond为什么要用这个公式呢？而且如果只是看maturity不可以从duration角度考虑么？如果debt上升，价格上升，yield下降，maturity不是会延长么？
品职答疑小助手雍 · 2019年10月07日
确实不严谨，使用http://class.pzacademy.com/#/q/16060这个链接里那个公式更合理一些。 后面那个问题没看懂，如果保持其他条件都不变的话，后面那些上升和下降从哪来的？
NO.PZ2016082406000039 Using the Merton mol, the value of the increases if all other parameters are fixeanI. The value of the firm creases. II. The riskless interest rate creases. III. Time to maturity increases. IV. The volatility of the firm value creases. I anII only I anIV only II anIII only II anIV only ANSWER: The value of cret-sensitive is B=Ke−(r+s)tB=Ke^{-(r+s)t}B=Ke−(r+s)t. This increases (1) if the risk-free interest rate creases, or (2) if the cret sprecreases, or (3) if the maturity creases. The cret sprecreases if the value of the firm goes up, or if the leverage goes wn, or if the volatility goes wn. Hence, the value of increases if the riskless rate creases or if the volatility creases. time to maturity 和 有关吗？ 应该是客观认为存在吧。 是混淆象吧
NO.PZ2016082406000039 Using the Merton mol, the value of the increases if all other parameters are fixeanI. The value of the firm creases. II. The riskless interest rate creases. III. Time to maturity increases. IV. The volatility of the firm value creases. I anII only I anIV only II anIII only II anIV only ANSWER: The value of cret-sensitive is B=Ke−(r+s)tB=Ke^{-(r+s)t}B=Ke−(r+s)t. This increases (1) if the risk-free interest rate creases, or (2) if the cret sprecreases, or (3) if the maturity creases. The cret sprecreases if the value of the firm goes up, or if the leverage goes wn, or if the volatility goes wn. Hence, the value of increases if the riskless rate creases or if the volatility creases. 为什么volatility会影响Firm Value？
Using the Merton mol, the value of the increases if all other parameters are fixeanI. The value of the firm creases. II. The riskless interest rate creases. III. Time to maturity increases. IV. The volatility of the firm value creases. I anII only I anIV only II anIII only II anIV only ANSWER: The value of cret-sensitive is B=Ke−(r+s)tB=Ke^{-(r+s)t}B=Ke−(r+s)t. This increases (1) if the risk-free interest rate creases, or (2) if the cret sprecreases, or (3) if the maturity creases. The cret sprecreases if the value of the firm goes up, or if the leverage goes wn, or if the volatility goes wn. Hence, the value of increases if the riskless rate creases or if the volatility creases. 老师这个题具体从哪个知识点来解析，（）只符合其中几个 我的想法是上升，V上升 1和2 都是下降的 3,4 都是上升的， 选不出来答案D
Using the Merton mol, the value of the increases if all other parameters are fixeanI. The value of the firm creases. II. The riskless interest rate creases. III. Time to maturity increases. IV. The volatility of the firm value creases. I anII only I anIV only II anIII only II anIV only ANSWER: The value of cret-sensitive is B=Ke−(r+s)tB=Ke^{-(r+s)t}B=Ke−(r+s)t. This increases (1) if the risk-free interest rate creases, or (2) if the cret sprecreases, or (3) if the maturity creases. The cret sprecreases if the value of the firm goes up, or if the leverage goes wn, or if the volatility goes wn. Hence, the value of increases if the riskless rate creases or if the volatility creases. 我不能理解（4）他说杠杆率下降，但是杠杆率等于A/E，当债务 上升的时候杠杆率应该是上升的，为什么杠杆率是下降的呢？
Using the Merton mol, the value of the increases if all other parameters are fixeanI. The value of the firm creases. II. The riskless interest rate creases. III. Time to maturity increases. IV. The volatility of the firm value creases. I anII only I anIV only II anIII only II anIV only ANSWER: The value of cret-sensitive is B=Ke−(r+s)tB=Ke^{-(r+s)t}B=Ke−(r+s)t. This increases (1) if the risk-free interest rate creases, or (2) if the cret sprecreases, or (3) if the maturity creases. The cret sprecreases if the value of the firm goes up, or if the leverage goes wn, or if the volatility goes wn. Hence, the value of increases if the riskless rate creases or if the volatility creases. B=Ke−(r+s)t 这个等式是指的啥啊