选择合适的选项补全对话。 A. What is the baby tiger doing? B. What can you see? C. What are they doing? D. What is she doing? E. Yes, I can. A: ________ B: I can see the mother tiger. A: ________ B: She's walking. A: ________ B: The baby tiger is running. A: Can you see any fish? B: ________ A: ________ B: They're swimming in the river.