Many years have been spent by him how to solve the question.
A. to learning
B. with learning
C. learning
D. on learning
网友回答
A. to learning
B. with learning
(答案→)C. learning
D. on learning
解析：句意：他用了许多年的时间来学习如何解决这个问题。句型：sb. spend（s） some time/some money (in) doing sth.,本句用的是被动语态，故选C。
考点: 考查动词句型的用法。