请教OG 12 第83题

wancheng100

原题如下。正确选项是B, 然而我选的是D。OG 对D 的解说是：The struction of this sentence is not parallel. 但是D不是在两个平行的reasons都用了现在式么？

83.In 2000, a mere two dozen products accounted for
half the increase in spending on prescription drugs,
a phenomenon that is explained not just because of
more expensive drugs but bv the fact that doctors are
writing many more prescriptions for higher-cost drugs.



(A)a phenomenon that is explained not just because
of more expensive drugs but by the fact that
doctors are writing

(B)a phenomenon that is explained not just by the
fact that drugs are becoming more expensive
but also by the fact that doctors are writing

(C)a phenomenon occurring not just because of
drugs that are becoming more expensive but
because of doctors having also written

(D)which occurred not just because drugs are
becoming more expensive but doctors are also
writing

(E)which occurred not just because of more
expensive drugs but because doctors have also
written

tommy8163

which 不能指代一句话，这里是同位语，所以在A B C中选，not but结构对称的只有B 和 C 了，定语从句和现在分词做定语的区别是：前者表示具体一次性，后者表示多次重复性，相比之下应该用定语从句，选择B

flames001

which 不能指代一句话，D其实就不用考虑了，
如要一个解释“The struction of this sentence is not parallel.”
not... but... 是一个平行结构
not just because... but because....  D缺少了第二个because 而不是因为分词而不平行

wancheng100

感谢两位大侠！