As a result, I used today to deal with some stuffs.

"Stuff" is considered an uncountable noun so the plural is still "stuff."

First, I went to the supermarket to buying some food.

I keep a diary before I go to bed, but sadly I was locked out due to thea low correction ratio.

I spent time correcting the journals in Chinese, and I so I have corrected half of them now.

It will cause the ratio to becominge too low and making me unable to write for a long time.

There were a lots of students, because the General Scholastic Ability Test is just on this Friday!

They reminded me thathow I also studied so hard before the exam.

Now, I still need to go to the library every day, but I have another purpose.

The same partimilarity between them is that I work hard for my future.

The library is closes everyd on Mondays.

As a resultTherefore, I used today to deal with some stuffs.

Or 'deal with some things' (I think that would be my first instinct to use!)

First, I went to the supermarket to buying some food.

'some' isn't wrong, but you already used it in the previous sentence, so I think things sound better if it's removed here.

Second, I had my hair cut.;

Connect to the next part using a semicolon

It iit's more convenient to shampoo it now.!

I would say 'easier' instead of 'more convenient', although that's fine too.

I keep a diausually write my diary entry before I go to bed, but sadly I was locked due to theout today because of my low correction ratio.

If you can replace 'due to' with 'caused by', then it's fine. If you can't, then use 'because of'. In this example, 'I was locked out today caused by my low correction ratio' doesn't make sense, so it should be 'I was locked out today because of my low correction ratio'

I spent some time correcting the journals written in Chinese, and I corrected've now done about half of them now.

Wow, speedy work!

I'm kind of afraid that the corrections I made are much less than Ia bit worried that I've made fewer corrections than what I will received, because there are not many journals in Chinese and I write every day.

I think 'worried' is a better choice here than 'afraid' or 'scared'. I also hope I've understood your problem here correctly!

It will cause thef so, my ratio will becominge too low and making me unable to write for a long timI'll be locked out and unable to write again for a while.

I think it makes sense to refer again to being locked out. (I hope this doesn't happen to you though!)

Today I went to the library today.

There were a lots of students, because the General Scholastic Ability Test is just on this Friday!

Your options are 'there were a lot of' or 'there were lots of'.

TSeeing theym reminded me that I also studied so hard before theat exam. –

Ggoing to the library had been my routine during that time.!

Connected to previous part now with an en rule :)

NowThese days, I still need to go to the library every day, but I have another purpose now.

The same part between them is IAs before, I'm continuing to work hard for my future.

As a result, I used today to deal with some stuffs.

First, I went to the supermarket to buying some food.

I keep a diary before I go to bed, but sadly I was [locked out | blocked] due to themy low correction ratio.

It will cause the ratio to becominge too low and makinge me unable to write for a long time.

There were a lots of students, because the General Scholastic Ability Test is (just) on this Friday!

“Just” sounds unnatural here.

They[Seeing them | Their presence] reminded me that I also studied sovery hard before the exam.

Now, I still need to go to the library every day, but I have another purpose.

ThWe same part between them is Ihare a common goal: we’re all working hard for myour future.s.

As a result, I used today to deal with some stuffs.

First, I went to the supermarket to buying some food.

Second, I had mygot a hair cut.

I keep a diary before I go to bed, but sadly I was locked out due to the low correct ratio.

I spent time correcting the journal entries in Chinese, and I corrected half of them now.

It will cause the ratio becoming too low and makinge me unable to write for a long time.

There were a lots of students, because General Scholastic Ability Test is just on this Friday!

The same part between them is I work hard for my future.

I wasn't sure how to correct this.