只说如果although在这里用在状语从句省略,2个问题。
IMO,
C:
1) we need a COMMA before although, such as D ( I have never seen the structure in C)------> 欢迎举出反例
2) if we put a comma before although, the sentence will be:--> appear on the surface of the Sun as dark spots , although never sighted at
" although never sighted at" ,the subject seems to be" dark spots." wrong
<reference: Along with the drop in producer prices announced yesterday, the strong retail sales figures released today seem to indicate that the economy, although growing slowly, is not nearing a recession.> (prep or Gwd source)
here "although.." ---> the subject is economy, right.
D:
although## -->the structure is ok, however the SUBJECT is wrong . thus U ONLY can regard "although##" as a subordinate clause which need subject and verb.
-- by 会员 Gail小M (2011/4/19 11:08:27)