when his parents are___work ,the little boy is in the house.用适当的介词或副词填空

问题描述:

when his parents are___work ,the little boy is in the house.用适当的介词或副词填空

at
at work
基本翻译
在工作;上班
网络释义
at work:在工作 | 忙于 | 上班