14. It's a place where you can enjoy blue water and beautiful mountains. (改為同義句) 

It's a place                 blue water and beautiful mountains.

13. [2014 •重慶A ] Cao Hua swims fastest in our group.(改為否定句)

Cao Hua              fastest in our group.

12. He told me,   " Don't open the present until Christmas Day." (改為同義句)

 He told me                  the present until Christmas Day.

11. The students have a trip to the Great Wall once a year. (對畫線部分提問)

                    the students have a trip to the Great Wall?

10. [2014 •黔西南〗I really don't know what I can do to help her out.(改為簡單句)

I really don't know what               to help her out.

9. New York is a wonderful city. It never sleeps. (合并為一句)

New York is a wonderful city             

8. Please tell me which one I should buy for my kids. (改為同義句) 

Please tell me which one                 for my kids.

7. To understand their accents is really difficult. (改為同義句)

          really difficult           their accents.

6. We will come back in a month. (對畫線部分提問) 

            will you come back?

5. Were they seen to get off the bus by their teacher yesterday? (改為主動語態(tài))       their teacher                 off the bus yesterday?