Explicação com vídeo: https://www.youtube.com/watch?v=X8lu4_5F0hg
Link 1: https://www.ego4u.com/en/cram-up/tests/simple-present-1
Link 2: http://www.englisch-hilfen.de/en/download/test_simple_present_en.pdf
Link 3: http://www.e-grammar.org/download/third-person-endings-2.pdf
