Mary and Lisa are sisters. They like the same colour— blue. They like the same sports— swimming and basketball. They go to the same middle school. But they aren't in the same class. They like music and art. Art is their favourite subject. 

But Mary and Lisa have a big difference (不同之处) . Mary has many friends. They like to play with her. But Lisa doesn't have any friends. Their mum sees the difference. She says to Lisa, "My dear, your smile (微笑) is very beautiful. Why not smile often?" Lisa says OK and she tries smiling often. Children come to Lisa. They like her smile. They want to make friends with her. Now Lisa has many friends. She is very happy.