为何题目计算contingent immunization都是用半年计算利息一次，但是题目又没有讲要半年。

2010年essay第六题

Frost recommends a technique called contingent immunization. Under certain market conditions, this technique can provide FT with a safety margin or cushion in meeting its liability. He notes that a U.S. government bond with a bond equivalent yield of 3.82% is available. FT agrees to implement contingent immunization using this bond.
B. i.Determinethe initial dollar safety margin. Showyour calculations. ii.Identifythe main advantage to FT of using contingent immunization rather than classical immunization.

题目只讲了用政府债券，没有讲半年计算利息，是不是所有contingent的题目都是假定了semi annual了。