[求助]另外几道语法题

我还有最后这几道题不明白,请高手们不厌其烦,帮我解答,谢谢! 求助的语法题分开贴了两个贴,请版主见谅呀!

1. The face is the most ____ of a human being.
A.part is distinctly
B.distinctive part
C.distinction in part
D. part of distinction
答案：A，我选了B

2. Today's nuclear fission fuels are the remnants of which used to be a much more active mixture of adioactive and fissionable materials two billion years ago and earlier.
答案：which
Which为什么错，应改为什么？

3. Petrography concerns primarily with the detailed description and classification of rocks, whereas petrology deals primarily with rock formation.
答案：concerns
Concerns应改为deals吧？可为什么deal...with可用于此句，而concerns...with就不行呢？

4．Lumbering, the remove of timber from the forest, is a major industry in the Northwest region of North America.
答案：remove
Remove应改为什么？

5.  The first city in the United States that put into effect major plan for the clustering of government buildings was Washington, D.C.
答案：plan
plan为什么错，应改为什么？

6. The orbit of a celestial body is usually in the shape of ellipse.
答案：of  ellipse
of 后接名词没错呀，Ellipse为什么错？