It was a mistake not to buy a better car

问题描述:

It was a mistake not to buy a better car
完成下面这个句子 要保持意思相同
必须用上only这个单词
If_______________________a better car.
THX

only I had bought
本句为虚拟语气
if only表示要是..就好了,由于是就过去事实相反所以要用过去完成时