完形填空。

Sandy is only four years old. She usually goes to the park with her grandma.

One day, Sandy saw some birds 1on the bench. She was very happy. She walked there and 2after the birds. Then a park keeper came up. He pointed to a sign on the grass and said, "Can't you see the sign?" "What does it mean?", asked Sandy. "It means you 3walk on the grass. Fine（罚款）ten yuan. " "Oh, sir. I only put one4on the grass. So I can only give you5yuan. "The park keeper smiled and said, "OK. You're lovely. I won't fine you. Don't walk on the grass again. "