牛人来看一道OG SC题 高人求解

zlljolie

14.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
C  appear on the surface of the Sun as dark spots although never sighted at
正确选项选A，OG解释说visible和sighted对应，C选项错在although后面应该跟句子，但是C中是短语sighted.

我觉得C也没错啊，状语从句不是有一种省略式吗，就是从句主语和主句主语一致，从句完整是although they have never been sighted at，这里省略了they have never been( sb be)。
牛人看看，这种想法不对吗？

universer

Although 加分词是状语从句省略形式 主语只能是sunspots 所以错了

zlljolie

Although 加分词是状语从句省略形式 这里如果省略的主语是sunspots ，完整形式是sunspots have never been...语意也是对的啊