从方框内所给的选项中选择恰当的句子完成此对话。（有两个多余选项）

A: It's really hard to say goodbye to our school.

B: You're right.  It's unbelievable that three years has passed.

A: Yeah, I still remember seeing you in Grade Seven.

B: Well. We used to be kids.

A: We've grown up with the help of our teachers.

B: And they're patient and kind, too.

A:  Gifts can express our thanks.

B: That sounds OK, but it's the best gift to go back to see them often.

A: I agree with you.

B: That's for sure.

A. How time flies! B. I don't think so. C. They are so helpful. D. But now we are teenagers. E. Why not buy them some gifts? F. Where can we get some gifts? G. They must be very happy to see us again.