There are no easy answers to questions brought to us by the rapidly changing world,        we can try to turn challenges into opportunities．

 (2012·南京高二检测) Some people are worrying about the possibility _______ mobile phones could be responsible for a range of illnesses, from rashes (皮疹) to brain tumors.

The government has taken some measures to solve the shortage of electricity , but it may be some time _________the situation improves.

Helen plays the piano well, ____her favourite instrument is the violin.

______ the Internet is of great help, I don’t think it’s a good idea to spend too much time on it.