It means, I believe, years of assiduous study and hard work on your part. And it is an achievement you can be well proud of.
我想这是你多年来刻苦学习和努力工作的结果，你应当引以为荣。
With my hard and assiduous study, I have achieved good academic achievements.
大学期间，我努力学习，刻苦钻研，取得了良好的学习成绩。
With my hard and assiduous study, I have achieved good academic achievements.
大学期间，我努力学习，刻苦钻研，取得了良好的学习成绩。
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