prep2-21的before的逻辑主语

Before scientists learned how to make a synthetic growth hormone, removing it painstakingly in small amounts from the pituitary glands of human cadavers.

(A) scientists learned how to make a synthetic growth hormone, removing it painstakingly

(A) scientists learned how to make a synthetic growth hormone, removing it painstakingly

(B) scientists had learned about making a synthetic growth hormone, they had to remove it painstakingly

(C) scientists learned how to synthesize the growth hormone, it had to be painstakingly removed

(D) learning how to make a synthetic growth hormone, scientists had to remove it painstakingly

(E) learning how to synthesize the growth hormone, it had to be painstakingly removed by scientists

答案是C，可是it 。。。和before。。。的主语不需要一致吗？后半句主语应该也是scientist吧？我怎么觉得D好一些？

我说说我的意见哈

说错了请指正

MM说的情况应该是介词+分词,才要看逻辑主语的

这里的before scientists…是个完整句子

当作时间状语用的

D的错误在那个it指代了a synthetic growth hormone在意思上是错误的

不过考试的时候哪想的到这么多啊~~~

谢谢MM

我做糊涂了，太多逻辑一致的病句，搞得我现在都这个都特别敏感。

這個問題事實上考的是指代啊～我第一次作也被騙了～

如果選D的話,it指的是合成的生長賀爾蒙,不合理，應該是生長賀爾蒙。