"Are you afraid of English tenses? Or verbs? You can practise tenses in English grammar exercises with answers online for free in gap-filling, matching or multiple choice exercises. Together with grammar rules they have been written by the experienced teacher who has been teaching for more than twenty years and they have been tested by hundreds of students of a language school. Some online tests are also available as printable tests with answers in the esl worksheets section."
This is the way the Czech site e-grammar introduces itself. I think I can add very little more to it other than saying that e-grammar has been a great unexpected discovery, as it allows us to revise and practise one of the key aspects of English grammar students have most difficulty with -tenses- and all the key structures where tenses are used (conditionals, reported speech, passive).
Thank you, Mgr. Petr Kulatý.