I stumbled across this great page yesterday. No only is there a summary of tenses and detailed articles on each one, but there’s exercises as well.
- Verb Lessons: Imparative Verbs in Portuguese (portugueseblog.org)
- The Future Perfect (englishbloggers.wordpress.com)
- Time : Past, Present and Future : Bhuta Bhavya Bhavan Nathah Vishnuh (ancientindians.wordpress.com)
- Present Deduction (englishelxni1.wordpress.com)