21.  You may find reputable and knowledgeable sites like libraries or specialized magazines recommend certain sites repeatedly.

22.  You can compare suggestions from several sites to make your final decision.

23.  You should have some sites in mind to help you search the Internet subject, keyword, and reference information.

24.  It's really inexpedient to squander time on online games and social networking sites.

25.  Geologists help to find meaningful historical sites; chemists then take good preservation of those cultural relics and assure the time of when they were made through analysing carbon atoms contained in.

26.  Secondly, nowadays there are thousands of pornographic sites on the Internet that can be easily found.

27.  These sites which have bad influence on our mental life are extremely harmful to everyone, especially to the kids.

28.  Many of them often wake up early , turn on their computer and chat on the Internet dating sites and instant-messaging progams-leaving their computer for only brief interval.

29.  The sites including violence and sex have been damaging the world so badly.

30.  These experts can also ensure the proper preservation of evidence found at the archaeological site.