A true friend is always helpful. I didn’t believe it 1 one thing happened to me when I was in Grade 7.
Li Jie was one of my classmates. He and I were also neighbours. He always listened to his mother 2 I didn’t like listening to my mother. I didn’t think it was necessary for 3 to teach me anything. Li Jie knew all about that but he said4 to me.
One weekend, Li Jie invited me to watch a film. I liked films very much so I went to the 5 with him happily. The film was about the love between a6 and her son. After watching it, I began to know how great the love of the mother was. I felt 7 that I didn’t listen to my mother before. I decided to think more about my mother than about8. After I told that to him, Li Jie smiled and said, “It’s really necessary for you to watch such a film. That was a good choice (选择) for both you and me.”
Suddenly, I knew9 he invited me to watch the film. Just at that time, I knew a true friend is always 10.

①若m=n，则|m|=|n|；②若m=﹣n，则|m|=|﹣n|；③若|﹣m|=|﹣n|，则m=﹣n；④若|﹣m|=|﹣n|，则m=n．