Half an hour has been made full of the problem.A. using; studyingB. use; to studyC. to u

问题补充：

Half an hour has been made full of the problem.

A. using; studying

B. use; to study

C. to use; to study

D. use; studying

答案：

A. using; studying

(答案→)B. use; to study

C. to use; to study

D. use; studying

解析：考查固定词组和句子结构。固定词组make full use of充分利用，本句是被动语态；第二空的不定式做目的状语。句意：半个小时已经被充分利用了来研究这个问题。故B正确。