Exercise 1 - Comma Splice and Run-ons: www.chompchomp.com/csfs01/csfs01.htm
grammar.ccc.commnet.edu/grammar/cgi-shl/quiz.pl/run-ons_add1.htm

Exercise 2 - Fragments:
www.chompchomp.com/frag01/frag01.htm
grammar.ccc.commnet.edu/grammar/cgi-shl/quiz.pl/fragments_add1.htm

Exercise 3 - Subject/Verb Agreement:
grammar.ccc.commnet.edu/grammar/cgi-shl/quiz.pl/sv_agr_quiz.htm

Exercise 4 - Punctuation Review:
grammar.ccc.commnet.edu/grammar/cgi-shl/quiz.pl/punct_quiz.htm

Exercise 5 - Confusing Words:
grammar.ccc.commnet.edu/grammar/cgi-shl/quiz.pl/confusibles.htm
grammar.ccc.commnet.edu/grammar/quizzes/notorious3.htm

Exercise 6 - They're, Their, and There / Its and It's:
grammar.ccc.commnet.edu/grammar/cgi-shl/quiz.pl/its_there_quiz.htm
www.chompchomp.com/hotpotatoes/wordchoice01.htm
www.chompchomp.com/hotpotatoes/wordchoice02.htm
www.chompchomp.com/hotpotatoes/wordchoice13.htm
www.chompchomp.com/hotpotatoes/wordchoice14.htm