I asked her whether she was enjoying her dinner 为什么用was enjo

首先说下enjoy这个词,一般都是enjoy+V.ing或n.,be enjoying sth 也不是什么固定搭配,
至于 I asked her whether she was enjoying her dinner 为什么用was enjoying
其实 I asked her whether she had enjoyed her dinner .在语法上完全没有错,
可能你说的那句有上下文关联,例如时间限制什么的,
I asked her whether she was enjoying her dinner at this time last month.这时指定时间了,最好用was enjoying而不用had enjoyed