I didn't manage to work out the problem _______the teacher had e
分类: 笔试(00004)发布时间: 2024-08-16 05:22浏览量: 4
I didn't manage to work out the problem _______the teacher had explained how. A、until B、unless C、when D、before 【正确答案】：A 【题目解析】：从原句时态及句意可知，用until表时间。unless表示条件，相当于if not。