求教Prep2007-CR-1，谢谢

沙漠之狐沉雨

To meet the rapidly rising market demand for fish and seafood, suppliers are growing fish twice
as fast as their natural growth rate, cutting their feed allotment by nearly half and raising them
on special diets.

(A) their natural growth rate, cutting their feed allotment
(B) their natural growth rate, their feed allotment cut
(C) growing them naturally, cutting their feed allotment
(D) they grow naturally, cutting their feed allotment
(E) they grow naturally, with their feed allotment cut  


我的疑问是
1. 为什么“suppliers are growing fish twice as fast as they grow naturally”这句话中they不会出现指代不清问题？难道是因为就近原则？
请问实战中到底怎样处理指代不清和就近原则？

2. “suppliers are growing fish twice as fast as they grow naturally” 中are growing和 they grow naturally是怎么构成平行结构的？are growing是正在进行时，是动名词吧，they grow naturally是句子吧，咋就平行了呢？

求大神指点，谢谢。

jxttsweet

是supplier are growing和they grow平行

myaska

我晕，这是道语法题吧？