Attend Your Classes Regularly 

It is now a very common phenomenon occurrence [1] that some university students are late for or absent from class now. So class attendance has become a thorny problem to for [2] both the students and teachers.
In reality, it is very important for the student to attend their classes regularly. First of all, it will ensure you [3] to catch up with the teachers in your learning. Thstudyat (??) is very helpful to you if you want to do a good job in your study. Secondly, attending class regularly is a way offers of showing respect to your teachers, too. Your teachers will feel bad if their students do not attend their classes, which, in turn, will may affect their teaching and may be harmful to students. Thirdly, attending classes regularly will help to form a good habit of punctuality, which is important for students [4] to do a good job in the future.
Therefore, as a university students [5], we [6] should form the good habit of attending our classes regularly from now on. And [7] Some day we'll benefit from it.

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[1] Being late to a class, or missing a class, is not a "phenomenon".  A phenomenon is something whose existence may be hard to understand.  For example: "Lightning is a natural phenomenon."

[2] Writing "a thorny problem to both students and teachers" is okay.  However, a native speaker is more likely to write "a thorny problem for both students and teachers".

[3] You have changed from writing in the third person to writing in the second person.  Within a single paragraph, you should keep the same perspective.  If possible, you should keep the same perspective across the entire essay.

[4] Now you have changed back from the second person to the third person.  

[5] In the following examples, please notice the different pronouns ('you' and 'we'), and how the different pronouns require consistent use of singular and plural forms:

"Therefore, as a university student, you should form..."

"Therefore, as university students, we should form..."

[6] Now you've changed to the first person.  A changing perspective can make it hard to read and understand a composition.

[7] Some people will say that you must never start a sentence with the word 'And'.  Personally, I think it's okay.  The reason I deleted it here is that it's simply not needed.