You must be aware the fact that it is great importance to learn English well.
A. to; of
B. of; of
C. to; in
D. of; in
网友回答
A. to; of
(答案→)B. of; of
C. to; in
D. of; in
解析：考察固定结构。Be aware of意识到…;of great importance=important重要；结合句意可知B正确。句意：你必须意识到这个事实，学好英语很重要。