It remains whether Liu Xiang will take part in the next Olympics.
A. to see
B. to be seen
C. seeing
D. to have seen
网友回答
A. to see
(答案→)B. to be seen
C. seeing
D. to have seen
解析：考查固定句型。句意“刘翔是否会参加下一届奥运会还有待观察。”It remains to be seen...“......还有待观察”。故选B。