They are swimming at the beach这句话对吗

They are swimming at the beach这句话对吗 They are good at swim.They are good at swimming.这两个表达方式都对吗?请 and they are very good at swimming in the Are they the children's books?这句话对吗? they are walking at the beach 和 they are walking on tht beac They are ice-cream.这句话对吗? They are cheap.这句话对吗? they are alomst children这句话对吗? Are they dumplings?这句话对吗 Are they calendars?这句话对吗? The children are _______ at the beach. He often went swimming in the evening 这句话对吗?