动物名词单复数区分 — 英语情景题

情景对话：放学路上，Sam 和 Lily 在回家途中看到一些动物，请选择合适的句子补全对话（只填序号）。 方框：A. It's a cat. B. They are dogs. C. It's a bird. Sam: Look! One cat! (1)________ Lily: Yes, it's cute. Lily: Now I see two dogs. What are they? Sam: (2)________ Sam: Listen! What's that in the tree? Lily: (3)________ Sam: How nice! Let's go home.