Mother wanted to know how much money he(?) on cellphones是had spent 还是spent

题目

Mother wanted to know how much money he(?) on cellphones是had spent 还是spent

答案

had spent
分析：
wanted to know 这件事已经过去了,他花钱是在wanted to know 之前的事,是“过去的过去”.所以要用过去完成时.