改错：I had dreamt of buying a car ever since high school.

had 改have .以下是分析：
ever since 的结构：(作为连词)=since “完成时态+ever since +主+动词简单过去式”或者“完成时态+ever since +过去的时间”
例：I have known him ever since he was a child.
他从小我就认识他了.
这种用法同since 差不多,不过 ever since 比 since 用得少.
再如：We have lived in Shanghai ever since we came to China.(自从我们来到中国之后就住在上海.)
此题中high school是过去的时间,因此用现在完成时!