解答一下OG SC14

iwillmissyouso

牛人来看一道OG SC题 高人求解
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), they就是指sunspots。
这种想法不对吗？

with二

although they have never been sighted at即使要省略也应该是although never been sighted at，那个表被动的been是不能省略的啊

iwillmissyouso

即使是用but have never been sighted...这个并列句的主语也是 sunspots， 而不是dark spots 啊

iwillmissyouso

although后面不是主动语态啊。不是有一种省略是，状语从句的主语和主句的主语一致，谓语是be, be后面是分词短语的话，从句主语和be可以一起省略的吗？

Fuckitup

When sighted 状语从句省略形式 动作的发出者必须是句子的主语即

sunspots 而非想表达得dark spots

with二

主语和助动词是可以省略的，但是被动语态是万万不能省略的啊
请lz再仔细读读C选项，although后面用的是主动语态呢