Dear Sir or Madam
I am a student of our university, who often spend my spare time in our library. Generally speaking, our library provides quite good service. However, I still have some suggestions for you to upgrade the quality of your service.
To begin with, I would like you to prolong the open time. In the daytime, most students are having classes. To continue, some books are too old/ are out of date. It would be better if you could replace them with updated materials.
I sincerely hope to have a comfortable library. And I would be highly grateful if you could take my suggestions into consideration.
翻译
亲爱的先生或女士：
我是我们大学的一名学生，我的业余时间经常在图书馆度过。总的来说，我们图书馆的服务很好。不过，我仍有一些建议供您提高服务质量。
首先，我希望你们延长开放时间。在白天，大多数学生都在上课。为了继续，有些书太旧／过时了。如果你能用最新的材料替换它们，那就更好了。
我真诚地希望有一个舒适的图书馆。如果您能考虑我的建议，我将不胜感激。