句型转换。 1. Is this racket yours? (同义句) Is this _____ ______? 2. There is one ball under the desk. (对划线部分进行提问) How many _______ ______ there under the desk? 3. Close the window, please. (否定句) ______ _______ close the window. 4. My trousers are black and white . (对划线部分进行提问) What _______ _______ your trousers? 5. The old man there is a doctor . (对划线部分进行提问) ______ ______ the old man there?