My answers.

When I worked at Lotte Mart as a part-time job, my manager provided us with a lot of works. One part-timers had a complaints, so he talked it to the manager. But the manager said “It is imperative that you all should work hard.” They had dispute over difference in opinion. After that Our workplace became very cold. I decided to resolve a dispute between them. First, I asked manager to have lunch with him , He agreed with my idea. As soon as they had a lunch, a part-timer make a polite apology. So they found solution, and our workplace became peaceful

Hi there! Thank you so much for your composition today! I appreciate your effort in doing your homework. Keep up the good work! You made a very comprehensive answer. I wish that I can help you the best way I can. Let us work hard together to improve your speaking skills. We can do it! Take care and have a wonderful day! T. Kelly^^ Here are my corrections for you: When I worked at Lotte Mart as a part-time job, my manager provided us with a lot of works. >>When I worked at Lotte Mart as my part-time job, my manager provided us with a lot of works. One part-timers had a complaints, so he talked it to the manager. >> Correct or >> One part-timers had a complaint, so he talked it over to the manager. (Better) But the manager said “It is imperative that you all should work hard. >> Correct (Nice sentence) >>But the manager said \"It is imperative that  all of you should work hard.\" They had dispute over difference in opinion. >> Correct or >> They had disputes over the difference in opinion. After that Our workplace became very cold. >> After that our workplace became very cold. I decided to resolve a dispute between them. >> I decided to resolve the dispute between them. First, I asked manager to have lunch with him , He agreed with my idea. >> First, I asked the manager to have lunch with him, he agreed with my idea. As soon as they had a lunch, a part-timer make a polite apology. >> As soon as they had a lunch, the part-timer made a polite apology. So they found solution, and our workplace became peaceful >> Correct or >> So they found a solution, and our workplace became peaceful. (Good Job!)