句型转换。 1. Is the book under the sofa? (做否定回答) ______, ______. 2. The keys are on the dresser . (对画线部分提问) ______ ______ the keys? 3. Is it in the backpack? (改为复数形式) ______ ______ in the backpack? 4. I know the teacher. (改为否定句) I ______ know the teacher. 5. They are on the sofa. (改为一般疑问句) ______ ______on the sofa?