he looks younger ,but he is older than me -three years.

问题描述:

he looks younger ,but he is older than me -three years.
A,since B,for C,about D,by

选D [他看起来很年轻,但他比我大三岁.]
注释:by可表示“(数量或程度)达到”,用于数词前.
又如:They overcharged me by 3 dollars.他们多收了我3美元.