131.Netizens between the ages of 18 and 30 are the driving force.

　　132.As the number of china's Internet users grows so does the junk mail.

　　133.Volunteers help develop backward regions.

　　134.have gone through a similar progression.

　　135.Following ringer tones(手机铃声) in popularity are games.

　　136.We've had a doubling of the number of a every month since 1999.

　　137.The coming month promise even more content.

　　138.in the very near future

　　139.acquire knowledge ("learn knowledge" is wrong!)

　　140.We study science to gain insight into the world we live in.