Sarah lives in the country, and she loves playing in the river near her house. But her father gets a new job in a big city, so she moves there with her parents. 

Their new house has a garden, but the garden is very small. Sarah is not happy in the new house. 

"Is there a river near here? " she asks her mother in the morning. Her mother answers, "No, there isn't. But there is a nice park near here and there is a pool in it. Shall we go there this afternoon? " Sarah is happy.

After lunch, Sarah and her mother go to the park. Sarah wants to play near the pool, but there is a sign (标记) before it. Her mother reads it to her, "Warning (警告): This pool is dangerous. Twenty people fall into (掉进) it. " Sarah looks into the pool carefully, and says, "But I can't see them. "