If you wanted to write a paper on how to check the validity of internet web sites, your main idea might be "tips to check the validity of internet web sites." one of your subtopics is that it is to see who authored the web site. which would not belong in letters 5, 6, and 7 above? is he or she a legitimate expert? is there a way to contact him or her? do they have a reason to be biased? web sites that end in "gov," "net," and "org" are often more reliable web sites