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.
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
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
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
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
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
我的解答：
首先namely是副词，不能连接整个句子。
A. the fact of 错，以为这里其实是要说明fact的内容，不是什么东西的fact，要用the fact that… 且本句是run-on句子.
B. 对. namely that they…中的that是代词，指代 feature. 但是其实也可理解为是that引导的同位语从句，可是逗号后面的同位语从句，绝对不能用that，而应该用which，所以这里可不可以是同位语从句，搞不准，请讨论。 所以这里如果能重现the feature或象C，D一样，用namely a considerable variation应该会更好吧。
C. it指代模糊，且和with n + n，无法形成逻辑的对应关系。
D. 同C
E. this fact无指代对象，且本句也是run-on句子 | 
