【题目】The machine has been used many years. It’s no wonder that it doesn’t work well________.
A. regularly B. constantly
C. occasionally D. frequently
在线课程【答案】C
【解析】
试题分析：A. regularly定期地，B. constantly 连续地，不断地，C. occasionally偶尔地，D. frequently经常地，句意：这个机器已经被使用了很多年，难怪它偶尔不工作了。所以选C。