“on and off” 的中文意思是 “断断续续地；有时；偶尔”。
例如：
I've had this headache on and off for a week.（我的头疼断断续续地持续了一周。）
He has been working on and off on this project for months.（他几个月来偶尔做做这个项目。）
“on and off” 的中文意思是 “断断续续地；有时；偶尔”。
例如：
I've had this headache on and off for a week.（我的头疼断断续续地持续了一周。）
He has been working on and off on this project for months.（他几个月来偶尔做做这个项目。）