用合适的句子补全对话。
A: Hi, Wang Fei. You look very unhappy. ____?
B: I failed the math exam yesterday.
A: ____. But you don't need to worry about it all the time.
B: I really don't know how to learn math well.____?
A: Maybe you can join our math group, so that we can help each other.
B: Sounds great.____?
A: Tomorrow, if you like it. I'm sure you will be better and better. Now, don't be sad!
B: Thank you so much. ____.
A: That's great!
