Present perfect with already, before, never, ever, yet

 

http://www.grammarbank.com/ever-never-just-already-yet.html

http://www.englishexercises.org/makeagame/viewgame.asp?id=3211

http://www.englishexercises.org/makeagame/viewgame.asp?id=2705

http://www.agendaweb.org/grammar/still-already-yet-exercises.html

http://www.carmenlu.com/second/grammar/presentperfect2_2.htm