I ate _ sandwich while I was waiting for _ 20:

问题描述:

I ate _ sandwich while I was waiting for _ 20:

怎么没选项呢。。。
根据已有部分来判断,大概意思是说当我在等...的时候吃了几个三明治

a him
我在20:08等他的时候吃了个三明治