Good day ma'am/sir! I am writing to you to show my interest on the job offer you are offering. I can assure you that I will be able to do job since I have been editing academic learning materials for half a year. I can also assure you that I will be able to finish it with the said deadline. Thank you
Being an English undergraduate in a well known state university in Sri Lanka, I think I'll be able to cooperate with you all in proofreading within a short period of time.