句型What is it? It's a... — 英语情景题

Tom 在夜晚的树林边听到奇怪的声音，和 Sam 玩猜动物游戏。请补全对话中所缺的句子（每空一词）。 Tom: Listen! Something is moving in the grass. (1)________ is it? Sam: I can't see it. Is it big? Tom: No, it's small and it has two long ears. Sam: Oh, I know! (2)________ a rabbit! Tom: Great! Now you ask me. Sam: There is an animal on the tall tree. (3)________ ________ it? Tom: (4)________ ________ monkey!