I spent half an hour _____ this difficult math problem.
分类: 英语（高升专）(c0003)发布时间: 2024-11-05 20:01浏览量: 0
I spent half an hour _____ this difficult math problem. A、having worked on B、to work on C、on work D、working on 【正确答案】：D 【题目解析】：spend +时间+doing sth 花费时间做某事；固定搭配