Extra exercises
- https://www.englisch-hilfen.de/en/exercises/questions/simple_past.htm
- https://www.englisch-hilfen.de/en/exercises/tenses/questions_answers_simple_past.htm
- https://agendaweb.org/exercises/verbs/past-simple/negative-forms
- http://www.adelescorner.org/grammar/past_tense/past_tense_negative.html
- https://agendaweb.org/exercises/verbs/past-simple/affirmative-negative-interrogative-write
- https://agendaweb.org/exercises/verbs/past-simple/affirmative-negative-write
- https://test-english.com/grammar-points/a1/past-simple-negatives-questions/