It’s necessary for usevery subject well.A. learnB. learnsC. learningD. to learn

问题补充：

It’s necessary for usevery subject well.

A. learn

B. learns

C. learning

D. to learn

答案：

A. learn

B. learns

C. learning

(答案→)D. to learn

解析：强调句式， It is adj for sb to do sth，做某事对某人来说怎么样。句意：对于我们来说学好每门课程很必要。结合语境可知选D。