Hello xujunjiejack! I feel some content would be better if changed.
1.
we are gonna discuss some cases experience how to be a judge.
we are going to discuss some cases to experience being a judge.
2.
"Student club" is a feature in my high school. All these student clubs are only established and run by students. Therefore, the club leader becomes an important role, who takes charge of the club.
I don't think this is really necessary. The admission officers know what student clubs are and how they work. Save the precious words for something else.
3.
Honestly, after I took over the club, I felt some invisible pressure around me.
The moment I had taken over as the president of club...
4.
the idea and laugh.
Filled with ideas and laughter
5.
I had an idea of quitting, but my promise in my first class stopped. I knew promises should obey.
I thought of quitting, but the promise in my first class that I wouldn't stopped me, because promises shouldn't be broken.
The discussion with my club members brought me the pleasure of changing thoughts; my preparation for the activities stimulated me to gain more knowledge ; my constantly speaking in front of club members also leads my speaking ability into a new level.
Use commas instead of semi-colons.
Hope this helped! :) Sorry if I've made any mistakes. I'm not a native English speaker.