A、An honest person never tells lies. B、One shouldn’t break a promise easily. C、An invitation is a sign of friendship. D、Somethin

　　I was excited as I had been invited to go to my friend’s birthday party. Tori was not my best friend, but she was in my class and we did stuff together. I asked my mom and she said I could go, so I told Tori that I’d be there. And then, two days later, (19) my best friend called and invited me to go to Disneyland with her. Disneyland! I really wanted to go... more than anything. I ran to ask my mom if it was OK. My mom reminded me that Tori’s party was on the same day. She said I couldn’t change my mind just because something better came along. (19)I begged my mom. She said no. I cried. My mom still said no. I couldn’t get her to change her mind. I tried every excuse I could think of. My mom explained to me again—once you accept an invitation to something, you can’t change your mind and go to something else just because you want to do the other thing more. (20)She asked me to think about if someone had said they’d come to my party and then, because something better came along, they changed their minds and didn’t come, how would I feel? So my mom dropped me off at Tori’s party. We did stuff that was fun and different. When my mom came to pick me up 1 told her all about the fun things we had done. (21)She told me that she was proud of me for understanding why I can’t just dump someone because something better comes along.
　　19. Why did the speaker cry according to the passage?
　　20. What advice did the speaker’s mom give to her?
　　21. What lesson did the speaker learn from her mom?