1.) used to do and 3.) are both in the past and imply that the action described (doing) is no longer being done. 2.) 1.) I used to do that but I do not do that now. 2.) I am used to doing that (and I still do that now). 3.) I was used to doing that (but I do not do that now/anymore). BTW : When is it correct (not correctly) Hope this helps John