The Online Writing Lab and Dr. Grammar both offer comprehensive, university-published websites that answer grammar and writing-related questions. These sites contain an exhaustive reference library of grammar answers, while the Online Writing Lab additionally offers a write-in question-and-answer service staffed by graduate student tutors.
To use the Purdue University Online Writing Lab's grammar resources, navigate to its website, select General Writing, and then select Grammar. This section is divided into a wide range of topics and also contains a link to grammar practice exercises. To ask a direct question from a tutor, select the OWL Mail Tutors link from the main page, and fill out the web form.
DrGrammar.org is run by the University of Northern Iowa. Clicking on the Frequently Asked Questions section produces an extensive, alphabetized list of common grammar-related questions.