阅读理解，根据短文内容填空。
The bird and the duck are going to see their friend, Mr. Cat. On the way there, they must（必须） cross（横渡） a river（河流）. When they get to the bank（岸边） of the river, the bird says to the duck, “We must fly across the river. ” “No. We must swim across the river, ” the duck says to the bird. They can't agree with（同意） each other. An old goat comes up to them and says, “You are both（双方） right. Birds are good at flying. Ducks are good at swimming. Don't judge（判断） things only by your own experience（经验）. ”
