由OG的两道题的一点小疑问

忘了在哪里看到的说although 是连词，后面必须接完整的句子，在og11-9里也得到了证明

9. Sunspots, vortices of gas associated with strong electromagnetic activity, are visible as dark spots on 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 darkspots 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

选E  排除C,D的理由是although要接完整的句子，要有完整的主，谓，宾

但og11-29题

29. Along with the drop in producer prices announced yesterday, the strong retail sales figures released today seem like it is indicative that the economy, although growing slowly, is not nearing a recession.
            

(A) like it is indicative that
            

(B) as if to indicate
            

(C) to indicate that
            

(D) indicative of

(E) like an indication of
        

为什么although又不是接完整的句子呢

那第一个的C选项为什么不能看作是省略呢？