It is important to have your eyes examined regularly to check for any sign of eye disease that may not have any ________.

The Sina Microblog provides a good ________ for those who want to express their opinions and exchange their ideas with others.

 It has always been the _____ of our firm to encourage workers to take part in social activities.

There was a tall boy sitting in front of me, blocking my _____ completely.

China has got a good          for fighting against the flu with its careful and smooth organization.