43. Five fledgling sea eagles left their nests in western Scotland this summer, bringing to 34 the number of wild birds successfully raised since transplants from Norway began in 1975.
(B) and brings

(C) and it brings

(D) and it brought

(E) and brought

答案是A，因为离开鸟巢和变成34是同时发生的，这个比较好理解。

关于C和D官方解释是因为 it 没有指代对象。在这里为什么it不能看作是指代前面整个句子呢？就是前面整件事情使得数目变成了34？

在从句中,以下连接词或引导词值得特别注意

which(或代词it)绝不能指代前面整个句子

肯定不能用it...

前面的主语是eagles,如果是and连接两个并列的句子，后面的物主代词it显然不能指代前

面的eagles

b,c,d exempt

题目的意思是，5eagles left this nests this summer,when they were leaving, they

brought 34 wild birds...

I am not sure my understanding is correct or not...