GWD4 31题，that主语从句那题

demorgan

GWD6-Q31:

The fact of some fraternal twins resembling each other greatly and others looking quite dissimilar highlights an interesting and often overlooked feature of fraternal-twin pairs, namely they vary considerably on a spectrum of genetic relatedness.

A.The fact of some fraternal twins resembling each other greatly and others looking quite dissimilar highlights an interesting and often overlooked feature of fraternal-twin pairs, namely they vary considerably

B.That some fraternal twins resemble each other greatly while others look quite dissimilar highlights an interesting and often overlooked feature of fraternal-twin pairs, namely that they vary considerably

C.With some fraternal twins resembling each other greatly and others looking quite dissimilar, it highlights an interesting and often overlooked feature of fraternal-twin pairs, namely considerable variation

D.With some fraternal twins resembling each other greatly and others looking quite dissimilar, it is a fact that highlights an interesting and often overlooked feature of fraternal-twin pairs, namely a considerable variation

E.Because some fraternal twins resemble each other greatly and others look quite dissimilar, this fact highlights an interesting and often overlooked feature of fraternal-twin pairs, namely they vary considerably

B为什么对？主语从句如何理解
D错在哪儿？很多人说it指代不清，但是这里it不是形式主语吗，是不是fact 修饰错误？改变句意？

HarrisZheng

D 首先 a fact 不能作为with some。。。的逻辑主语
其次 it is。。。 that。。。句式里，it不是形式主语，整个句式是强调句型

demorgan

多谢，也就是说D的错是再with some逻辑主语，it还是没有问题的，对吧？
另外主语从句什么情况下使用呢，有什么要注意的吗，多谢~