There is an elephant and a monkey. They're friends. But one day they want to know who is stronger （更强壮）. One of them says, "Who can get apples from the tree across the river, who is stronger."The monkey says, "I can't swim." The elephant says, "I can swim. Please sit on my back."Thus they go across the river. The apple tree is very high. The elephant can't reach the apples on the tree. The monkey climbs（爬）up the tree and gets many apples. Now they know they should help each other.