单词学习：back and forth 副词短语
back and forth
/ˌbæk ən ˈfɔːrθ/
来回地；反复地
Mr. Gu walked back and forth in the classroom while explaining the grammar rules.
顾老师在教室里来回踱步，同时讲解语法规则。
单词卡片
卡片已就绪
