You need to understand, that you have to follow specific format, in order to write a good application letter.
Here, you need to know and remember 2 important things
1. Why do you need to use library?
2. ***Number of days, you want to use it (Justify your action by mentioning the specific days like from 7th May, 2018 till 15th April, 2018)***
Now, check the following letter
Yes, you have to say things in a short and precise manner, since an application letter comes under the category of Formal Letter
I am writing the following letter to the Librarian requesting him/her to permit me use library
City Montessori School,
Subject (Request to issue a book )
I am X (Your name) student of Class 10th A, requests you to kindly permit me to use library
I can constructively pass my time after school with such a wonderful place which is a jewel of information.
Considering the approaching exams, I can refer various relevant notes and act read in a peaceful environment. While visiting the library, last time I was pleasantly surprised, considering the list of information and guidance which I can possibly get.
I will be really pleased, if you can give me permission to use it.
I will assure you, that I will only visit the library, in the free time, without jeopardizing the regular class subjects.
I won’t give you any reason for any complaint as well.
I am looking forward for your favorable response,
I will be highly obliged,
Thank You in advance ,
Class 10th Student