英文IQ题
Alambisveryhungryandhewantstoeatsomegrass.Underatalltreethreeisanicebigpatchoffreshgreengrass.Butafiercedogistiedtothetreeandwillnotletthelambcomenear.Atlast,thelambhasanidea.Heusesittoputwitthedogandeatthrgrass.Canyouguesswhatthelambdoes?(中文回答)