14 A migraine typically afflicts one side of the head, lasts for hours or days, and may recur as infrequently as once every other month or often, as daily.

a) as infrequently as once every other month or often, as

b) as infrequently as once every other month or as often as

c) infrequently, as often as once every other month, or often, like

d) infrequently, like once every other month, or often, like

e) infrequently, like once every other month, or as often as

大全上的答案是b。这里的比较结构我有点不懂。as infrequently as连接的是recur 和 once every other month,可是recur 和once every other month 是不同类的怎么可比呢？

如果是省略的话，记得有好多a is as...as b 的题不都是 都要把b中的动词或助动词补出来才对么？

as infrequently as once every other month ，as 连接的是infrequently和 once every other month ，都表示频率，可比较；第二个as---as是as often as金山词霸是“每当”的意思，我想在这里是表示经常的意思吧。