---Have all the mysteries been cleared up?
--- Almost. But only one question .
A. there remains; answered
B. it remains; to be answered
C. there remains; to be answered
D. it remains; answered
网友回答
A. there remains; answered
B. it remains; to be answered
(答案→)C. there remains; to be answered
D. it remains; answered
解析：考查there be 句型及不定式作定语。句意：---所有的谜团都解开了吗？---几乎都解开了。只剩下一个还未解决。There remains…是there be句型的变形，第二空to be answered是不定式的被动做定语，表示“有待解决”，选C。