Or go to the Companion Site for our text, The St. Martin's Guide to Writing You will need to sign in as a student. You do not need to enter any email address. You will see three sections and lots of exercises. Digital Education Network's Test Centre . You will have to log in, but it's free and full of exercises.
Answers are available through a link at the bottom of the exercise pages.
In addition, there are pages of explanation and examples of each tense to which you can refer if you need help on the exercises. Writing Sites Proofreading for Commas - Follow these seven steps for a paper with no comma errors. Direct and Indirect Quotation - this page has explanation and examples with an exercise and answers.