Forms 6a,6c. Present Continuous. Present Simple.

For practicing:
http://www.perfect-english-grammar.com/present-continuous-exercise-6.html;
http://www.englisch-hilfen.de/en/exercises/tenses/present_progressive_mix.htm;
http://www.really-learn-english.com/present-progressive-exercises.html#01;
https://www.englisch-hilfen.de/en/exercises/tenses/simple_present_progressive.htm;
https://www.englisch-hilfen.de/en/exercises/tenses/simple_present_progressive2.htm;
http://web2.uvcs.uvic.ca/elc/studyzone/330/grammar/simcon1.htm;
https://elt.oup.com/student/solutions/preint/grammar/grammar_01_012e?cc=lt&selLanguage=en;
https://www.englishgrammar.org/simple-present-present-continuous-tense-exercise/;
http://www.myenglishpages.com/site_php_files/grammar-exercise-present-continuous-present-simple.php.