根据对话内容，在横线处填入正确的单词，使对话完整。
A: What are you doing, Bill?
B: We are raising money for "Helping Future Project".
A: I have __1__ heard about it before. What is it about?
B: It is aimed to help poor and homeless kids in different parts of the world.
A: What a great charity! I also want to __2__ some money.
B: Really? All poor and homeless kids will be thankful to you for your __3__.
A: But I'm __4__ I can't donate too much. You know, I'm just a student and I don't have much money. I
can only donate 200 yuan.
B: That's __5__. A sincere heart is the most important. Thank you very much.