根据语境，用恰当的语言完成对话。
A: Good morning, Mary.
B: Good morning, Helen. Come in, please.
A: Thank you. Your room is very nice. Oh! A bookshelf and many books. 1______
B: Thank you. I like reading, you know. I think reading can make a person wise.
A: Did you do well in the English exam?
B: Yes. I just learned I passed the English exam and the result is good. I have got an "A".
A: 2______
B: Thank you. 3______ Why?
A: We will have a math exam next Monday. I'm afraid I may fail the exam. So I've come for some help.
B: Don't worry. 4______
A: That's great. Thank you very much.
B: 5______ A friend in need is a friend indeed.
A: That's true. When shall we start?
B: Right now.
1. I know why you are so good at your lessons. / I know why you study so well. /
I think that's the reason why you study so well.
2. Congratulations!
3. But you look worried.
4. I can help you.
5. It's a pleasure. / You're welcome. / Not at all.
(答案不唯一)