You must be aware the fact that it is great importance to learn English well.A. to; ofB.

问题补充：

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

答案：

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。