请用所给的代词填空。 this, that, these, it 1. _______ keys are mine. That is yours. 2. What's ________? It's an egg. What's ________ over there? It's an orange. 3. Look at ________ pencils. Are they Lucy's? No, these aren’t hers. 4. Hi, Mum, ________ is my friend, Lucy. 5. What is it? ________ is an apple.