1. There is a pencil on the desk. (改为一般疑问句) 
                                   a pencil on the desk?
2. Does he often skate in winter? (作肯定回答)
                   , he                .
3. The children cleaned the library last Monday. (改为否定句)
    The children                                 the library last Monday.
4. You will meet your friends at the railway station,                 you? (完成反意疑问句)
5. Those birds are very beautiful. (改为感叹句) 
                     beautiful those birds are!
6. The Young Pioneers are making model planes. (改为疑问句)
                                         the Young Pioneers making?
7."Don't open your books!" the teacher said to us. (改为间接引语)
    The teacher told us                                                                  books.
8. Did they sell out this kind of computer? (改为被动语态) 
                    this kind of computer                 out?