选C think about
think about表示下列意义时一般不和think of换用.
①"回想"过去的事情.eg:
We mustn't think about this matter any more.我们不许再想此事.
②"考虑"某事,某计划是否切实可行.eg:
I'll think about your suggestion and give you an answer tomorrow.
我要考虑一下你的建议,明天给你答复.为什么不选B呢表示回想过去的事情的时候只用think about，应该属于惯用型。