变疑问句和否定句：The exam begins at nine.Ann returned the book to the library yesterday.
问题描述：
变疑问句和否定句：The exam begins at nine.Ann returned the book to the library yesterday.
答
原问句:What time does the exam begin? (通用回答有明确的时间，我们会用what time来问)
疑问句：Does the exam begin at nine? (在does後的动词begins要变回原形动词begin)
否定: No, it doesn't.
疑问句: Did Ann return the book to the library yesterday?
(在did後的动词returned要变回原形动词return)
否定: No, she didn't.
答
when does the exam begins?The exam doesn't begin at nineDid Ann return the book to the library yesterday?Ann didn't return the book to the library yesterday.