问题如下：
How is the yield to maturity on a bond affected by its coupon when the yield curve is (a) flat, (b) upward-sloping, and (c) downward-sloping?
解释：
When the yield curve is flat so that all rates equal R, the yield to maturity of a bond always equals R. When the yield curve is upward-sloping, the yield to maturity decreases as the coupon increases. When the yield curve is downward-sloping, the yield
这题是在考察什么呀，学晕了，老师请帮我再明确下知识点，谢谢
