急：although作为连词，之后主谓不能省？

although作为连词，之后主谓不能省？能说although to do/ doing/ n/ adj???

是不是连词后面一定是完整的句子？

谢谢

这样抽象讨论GMAT SC总结出来的“规律”

实战意义不大

还是放在题目里面"比较"有用些

885-sec 19-4

Sunpots, vortices of gas associated with strong electro-magnetic activity, appear on the surface of the Sun as dark spots although never sighted at the Sun's poles or equator.

这个题大全中是上面的正确答案，og11中og说：although后面缺少主语，although要连句子。大家看，上面句子错误的理解是？？