he has been studying computer science on and off for five years的翻译：he has been studying computer science on and off for five years 什么意思？中文翻译英文，英文翻译中文，怎么说？

青云英语翻译

他一直在研究五年和关闭计算机科学

he has been studying computer science on and off for five years

He has been studying computer science on and off for five years

he has been studying computer science on and off for five years