Mr. White works in a park. He can't hear or speak. He looks after the chairs in the park. Some chairs in the park look very old. Mr. White wants to paint   them. It is cloudy today. There are few people in the park,so Mr. White starts to paint a chair. After he paints it,he goes back to his office and brings a card with "WET PAINT" on it. He wants to put the card near the chair. He takes the card and walks to the chair. Dave is taking a walk in the park. He feels a little tired  .He wants to sit on a chair. He sees the chair. He is walking to it,too. Mr. White finds someone behind him walking to the same chair. He walks quickly. When Dave sees this,he begins to run. Mr. White begins to run,too. Dave runs faster than (......)Mr. White and he sits on the chair. He does not know the paint is wet. Mr. White is not happy to see him sitting on the chair. He shows Dave the card. Dave feels very embarrassed  . Mr.White's job is to   _  .
clean the park grow trees help people in the park look after the chairs in the park