Key points:
1.It's Sunday.

2. Look, the boy is Jiamin, and the girl is Sally. They're friends. They are greeting to each other.(正在打招呼）

3.
Jiamin: go to Tianhe Book Center, buy some books, with his mum, by underground, invite（邀请） Sally to go together.
Sally: Agree(同意）, go to the bookstore with Jiamin.

Boys and girls, try to make your own dialogue with your partner. You can do it!(请尽最大努力跟同桌对话，你能行的！）