Calculating portfolio duration as the weighted average of time to receipt of the aggregate cash flows:
A. accommodates portfolios that include callable bonds.
B. facilitates the evaluation of the effect of benchmark yield changes on portfolio value.
C. results in a theoretically correct but less commonly used measure of portfolio interest rate risk.
解析：選C。通常久期的計算是單個債券久期的加權平均值，題干中的做法不常用，但理論上正確。A項，為*現(xiàn)金流確定性，不能包括嵌入期權或FRN。B項，現(xiàn)金流收益率的變化可能與基準收益率不同，所以”有助于“的說法不正確。
Which ... relating to yield volatility is most accurate? If the term structure of yield volatility is downward sloping, then:
A. short-term rates are higher than long-term rates.
B. long-term yields are more stable than short-term yields.
C. short-term bonds will always experience greater price fluctuation than long-term bonds.
解析：選B。題干設定收益率波動(yield volatility)的期限結構向下傾斜，因此短期收益率波動高于長期收益率波動，即長期收益率較為穩(wěn)定。A項說的是 rates，C項說的是 price，和 yield 不能等同。
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