关于Although的用法

CJRandis

刚看到这个题目
Sunspots, vortices of gas associated with strong electromagnetic activity, are visible as dark spots on the surface of the Sun but have never been sighted on the Sun's poles or equator.

(A) are visible as dark spots on the surface of the Sun but have never been sighted on
(B) are visible as dark spots that never have been sighted on the surface of the Sun
(C) appear on the surface of the Sun as dark spots although never sighted at
(D) appear as dark spots on the surface of the Sun, although never having been sighted at
(E) appear as dark spots on the Sun's surface, which have never been sighted on

看到一个解释说"although", however, can be followed by an adjective or adjective phrase: james, although bigger than many of the other players, is one of the fastest men on the team.
那么提个问：1.是否Although后面只能接句子
2.此题D后面although引导的句子是否是个省略句？

CJRandis

张风儿 发表于 2015-12-11 19:21
OG13 17题，OG12 14题
Sunspots, vortices of gas associated with strong electromagnetic activity, are  ...

十分感谢，我都弄明白了。