大全299 请教

Florida will gain another quarter-million jobs this year alone, many of them in high-paying fields like electronics and banking, making the state’s economy far more diversified than ten years ago.
(A) high-paying fields like electronics and banking, making the state’s economy far more diversified than
(B) high-paying fields like electronics and banking, and making the state’s economy far more diversified than its economy
(C) high-paying fields such as electronics and banking, to make the state’s economy far more diversified than
(D) such high-paying fields as electronics and banking, making the state’s economy far more diversified than it was
(E) such high-paying fields as electronics and banking, and make the state’s economy far more diversified than it was

想请问下making  and to make 在这个题目中的区别？也就是分词与不定式在这种成分时的区别？

不定式表目的，现在分词表伴随，这两个东西一旦出现一般是不能互相替换的，而且c里的than前后比较对象也不对等。

选项C

Florida will gain another quarter-million jobs this year alone, many
of them in high-paying fields such as electronics and banking, to make the state's economy far more diversified than
ten years ago.
        

就句意推，找to make的动作发出者，由于many前后有逗号故是插入语，故to
make是由Florida发出，变成Florida为了要多样化所以gain工作。

选项D

Florida will gain another quarter-million jobs this
year alone, many of them in such high-paying fields as electronics and banking,
making the state's economy far more diversified than it was
            ten years ago.

to make改成making，可以清楚表示修饰前一句，讲一个因果关系，什么造成多样化？是许多在高薪领域的工作，many
of them修饰前一句，然后making修饰many of them。

Correct me if I am wrong

One of the earliest known birds with a beak and contour feathers, Confuciusornis
sanctus, had large clawlike “thumbs” on its wings, probably
to help it climb up to a launching position for flight.

这也是我不明白的问题之一: than后面的it was为什么不能省略? 有没有什么情况下，是可以省略的？

精华里的比较之疱丁解牛篇里有这样的句子: Rice has protein of higher quality than usual/ever before/1000 years ago/people expected(状语比较）意义：米比通常/经往/多年前/人们预测/的蛋白质质量要高。

按照本题的逻辑, 是不是这样的句子也是错的, 应该改成: Rice has protein of higher quality than it did 1000 years ago?

请指教.