Hello Such. How are you?

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The internet-a blessing or curse"?

Nowadays,         [Such,  the term  "Nowadays" is  a very trite usage.

It goes without saying  "nowadays" that you are writing in the context of contremporary affairs, so eliminate the word from your introduction, okay?

The Internet is widely used in many fields especially in compus ["compus" = campus, correct?]

Some people think it is harmful for college students to use  the Internet but others object it.  [Yes, but who is it in specific who  thinks one way or the other?  Quote some authorities on the subject. Otherwise, you are just publishing a common logical error designated the Fallacy of the Dicto Simpliciter ("Sweeping Generalization")]

 In my opinion,I am  in agreement  with the former.  That is,   I think the Internet is a  curse to university students.
There are dozens of reasons supporting my idea, [Okay, but unless you are  using

"dozens" of examples, it will be better to write something like:

 "There are several reasons I might cite, as follows.]

The first reason is that they can't shedule their time properly.

Most  students spend most of their  time playing computer games,

watching videos or chatting with friends.

They seldom use the  machine to enlarge their knowledge or study.

There is no doubt that they waste their time on Internet.
What's more, [A  most excellent transitional phrase. Very good, Such!]

   What's more, it takes long time for them to interface with the computer,

so they seldom play sports and lack of exercise  is a unhealthy.

Also,   due to   interface with the  screen,  their eyesight  becomes much poorer.
In  conclusion,  f the college students can't use the  Internet appropriately,

it will be harmful for them.

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    A most excellent, and lengthy essay.  Very good indeed!---Warm regards, Bruce