I have a few experiences

Hi [이름]!

Make sure to take note of the proper use of conjunctions and modifiers.

Look especially at the correct way to begin your sentences.

Practice more.

You can do it!

~~ Teacher Sharon

Until I was a university student, I couldn\'t say ’No’ to my friends.

>> Correct
This is because I was afraid to say ’no’ to my friends.

>> Correct
However, I realized that if I don\'t say ’no’, I have to take risks.

>>  However, I realized that if I didn\'t say ’no’, I had to take risks.
Once, my friend wanted me to submit her assignment because she wanted to go out.

>> Correct
But I had to go to class.

>> At that time, I had to go to class.
So, I said ’No’ to my friend.

>> Correct