根据短文内容，判断正误。

It is nine thirty in the morning. Mr. Green and his students are going out on a picnic. They're in the park now. The children are having a good time at the moment. Look, the girls in the beautiful dresses are Su Hai and Su Yang. They're singing and dancing. Where is Mr. Green? He is playing games with Helen and other students." But Liu Tao and David are fishing near the river. Then a park keeper comes up to them. He points to a sign near the river. He says to the boys, 'Can't you see the sign over there?' It says 'No fishing, please.' Liu Tao and David say sorry and leave there quickly.