http://www.englishexercises.org/makeagame/viewgame.asp?id=5693
http://www.ecenglish.com/learnenglish/lessons/simple-present-tense-negative
https://elt.oup.com/student/project3rdedition/level1/unit4/grammar/exercise3?cc=hu&selLanguage=hu


http://www.juntadeandalucia.es/averroes/torredelprado/ingles/present_simple1.htm
http://www.englishmaven.org/HP6/Present%20Tense%20Exercise%204.htm
http://www.englishmaven.org/HP6/Present%20Tense%20Exercise%206.htm
http://www.english-4u.de/present_ex2.htm