答案：A

题目分析：考查固定词组，A. made up his mind下定决心D. made his mind决心，其短语made his mind to do sth意思“决心做某事”，句子意思“一旦他下定决心，什么也改变不了他的注意”

点评：固定词组是高考常考内容，本题考查由mind组成的短语，意思各不相同，要求考生应牢记

即学即练：They chatted a lot on the phone and helped the girl            the awful days and always put her in a good mood.

A.get through        B.get out            C.get away          D.get into

选A