Years of school life had （ 改为has ) taught me a lot of things,of which teamwork is the most important for me.
In fact,I didn't realize it until I was being ( 去掉being ）chosen monitor of my class in my senior middle school.At first,I did most of the duties myself while other student （ student加s )cared little about class activities.As the (改为 a) result,I was tired out and fell (改为 felt ) unhappy.Then I turned to my teacher and he advised me ( 加 to )cooperate with others.So I had a good talk to ( to 改为 with ) my classmates for their ideas.They soon understood me and began to doing (改为 do ) what they should in class.
Teamwork have freed me of trouble and made my work much ( 加more ) effective then ( 改为than ) ever.