Knock Knock,Trick or treat,Who are you? I'm a ghost(幽灵). I'm a little ghost. Knock Knock,Trick or treat,Who are you?I'm a cowboy(牛仔). I'm a little cow...boy. Knock Knock,Trick or treat,Who are you?I'm a witch(巫婆). I'm a little witch. Knock Knock,Trick or treat,Who are you?I'm a monster(怪兽). I'm a little monster. Knock Knock,Trick or treat,Who are you?I'm a ballerina(芭蕾舞女演员). A little ballerina. Knock Knock,Trick or treat,Who are you?I'm a pirate(海盗). I'm a little pirate. Knock Knock，Trick or treat.Happy Halloween! Happy Halloween!