I have bought a good book, ______ that will surely interest         of the students．

(2013·开封市高三二模) The power failure made ________ difficult for us to complete the task on time.

___ is everyone’s duty___ the law.

 Of all the methods they provided, ________ is of any help for solving the math problem.

Many people agree that there has never been a more splendid opening ceremony than _______ of the Guangzhou Asian Games in history.