TOPIC 

Should minors who commit serious crimes receive the same punishments as adults?

POINTS
・Financial costs ( I chose )
・Mental maturity
・Public safety
・Justice
・Prison life ( I chose )
・Schooling ( I chose )
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　*I think minors who commit serious crimes should not receive the same punishments as adults. I have three reasons to that support my idea. *(Try to avoid using the pronoun "I" when writing an essay, especially a persuasive one.)
　Firstly, we cannot expand prison anymore viewing because of from the point of finacial financial costs. we cannot expand prison anymore (moved this phrase to the front of the sentence to make this sentence in active voice rather than passive voice. Active voice is usually prefered when writing an essay).  Due to lack of budget, I hear that some local government has faced the quandary that of not being able to they cannot maintain the prison facilities. because of lack of budget. (moved the crossed out portion to the beginning of the sentence). What is worse, the number of prisoners is are getting higher year by year. Also *We have to consider building seperate prisons only for children because they are still young. *(Are you suggesting that building these prisons only for children will make it more of a financial problem?  I think you should have the fact of their age be in the next paragraph since it deals with the condition and development of children. You also make it unclear what the "same punishments" children would be facing that adults have to face. You may want to make it clear you are talking about child prisons.)
　Secondly, even though we built prisons for children, from the point of prison life, prison it is not a good condition for has a negative effect children. I often hear that there are bullies in prison, and this is very tough for mentally immature children. (Try adding another sentence after this one that concludes and transitions into the next topic).
　Thirdly, after children prisoners came come back from the prison, I think they cannot go back to the usual schooling. They cannot enjoy school life as like other kids. (Why can't they enjoy school life like other kids?) Nowadays, young children use social network services like Twitter and Facebook. Because of their prison experiance, there is a dangerous higher possibility that they children prisoners will suffer from net cyber bullying. Nowadays, young children use social network services like Twitter and Facebook, which make it easier to bully one another. 
　As you can see, once children got the same punishments as adults, they cannot go back to normal life as other kids. Therefore, I think they should not receive the same punishments as adults.

208 words

I hope I was able to help you with grammar and offer you good suggestions for your writing! If you have questions on my editing, please don't hesitate to ask. I hope my comments aren't too confusing!