关于as...as的问题

请教一下两个问题

1 but not 和 rather than 是不是都只能 接名词，不接句子？

2 They are as disturbing to A as they are disturbing to B.这个句子省略到什么地步可以呢？还是一点都不能省？

   They are as disturbing to A as they are  to B.   They are as disturbing to A as to B.      都对不对呢？

   另外这句话呢？They are as disturbing to A as compelling to B. 一定要补全they are吗？

谢谢指点！！！

Though certain breeds
of dog are renowned for their sense of smell, there is often a greater
difference in scenting ability between two members of a single breed than
between members of different breeds.

1、我说的不是not...but,就是but not,和rather than 一样用，这个结构在GMAT中不优选，出现的都是错的。但如果能确定rather than加名词性短语，应该but not 也是。

2、原来这种结构是比较少见的。看来，如果两形容词不一样，主谓就不能省；若相同，主谓都可省，只留下不一样的部分。

谢谢啊！