英语智力题!A lamb is very hungry and he wants to eat some garess.

英语智力题!
A lamb is very hungry and he wants to eat some garess.Under a tall tree is a nice big patch（块）of fresh green garss.But a fierce(凶猛的）dog is tied to the tree.The lamb has an idea.He uses it to put wi(以机智胜过）the dog and eat the garss.Can you guess what the lamb does?(You can answer in Chinese.)
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