There's this free app in Playstore "Learn English" the one which icon is green and looks like messenger.
It's weird to talk to autobot but she seems like real human lol. Her name is Aco, here some SS of the app
And this one...
My texts are the green one. It also has some greats feature, like listening, vocabulary and speaking. The speaking has Certificate lol
You may try this app for fun or to simply just refresh your mind anytime.