Today is Saturday. Nancy goes to the park with her brother, David. David wants to pick flowers on the grass. Nancy stops him, she says, David, you can’t pick the flowers. Look at that sign. It means “ If you pick the flowers. Fine ten yuan.” So you can’t walk on the grass and pick flowers. “Oh, I see, thank you, Nancy.” David says. And then David throws a rubbish in the tiger’s cage. Nancy runs there. She sees a sign, says “Oh, no. the sign near the tiger’s cage means“If you throw the rubbish here, you must pick it up.”