英文IQ题A lamb is very hungry and he wants to eat some grass .U

英文IQ题
A lamb is very hungry and he wants to eat some grass .Under a tall tree three is a nice big patch of fresh green grass .But a fierce dog is tied to the tree and will not let the lamb come near.At last ,the lamb has an idea.He uses it to put wit the dog and eat thr grass.Can you guess what the lamb does?（中文回答）