Could you please provide feedback?

From what I could see (the "try it free" links didn't work), this is mostly grammar drills. There are a lot of sites that offer that, and that isn't really the way people learn languages. What are you going to have for speaking exercises? That's the hardest thing to provide online. Exercises should be contextualized, and you might attract users by having highlighted exercises on those particularly difficult aspects of English, like two-word verbs, preposition usage and idioms. I also really wish you would not perpetuate the incorrect idea that English has tenses other than present and past. The others are aspects. You could just avoid using the word "tense"- call the verb a present progressive, for example. Tenses are endings on verbs that change the time reference, as in Spanish. English doesn't have those- we put pieces together to indicate the time frame.