Online dictionnaries
https://www.wordreference.com/
https://diccionario.reverso.net/
General
https://www.mansioningles.com/ejercicios00.htm
Present Simple
Basic:
https://agendaweb.org/verbs/present-simple/index.html
https://agendaweb.org/exercises/verbs/present-simple.htm
https://www.montsemorales.com/gramatica/PresSimp1.htm
https://www.english-room.com/4_01.htm
https://www.english-room.com/presentsimple_03.htm
https://www.english-area.com/paginas/presentesimplequestionsnegative.htm
Intermediate:
https://www.focus.olsztyn.pl/en-simple-present-exercises.html#.Wd8qtopLeRs
https://www.englishexercises.org/makeagame/viewgame.asp?id=2829
https://www.montsemorales.com/gramatica/PresSimp5.htm
https://www.tolearnenglish.com/exercises/exercise-english-2/exercise-english-3427.php
https://www.englisch-hilfen.de/en/exercises/tenses/simple_present_mix2.htm
https://www.perfect-english-grammar.com/present-simple-exercise-9.html
https://www.esl-lounge.com/student/grammar/1g1-present-simple-gap-fill.php
Present Continuous
https://agendaweb.org/verbs/present-continuous/index.html
https://www.carmenlu.com/first/grammar/presentcont17.htm
https://www.montsemorales.com/gramatica/PresCont2.htm
https://www.englisch-hilfen.de/en/exercises/tenses/present_progressive_negation_contracted2.htm
Present Simple VS. Present Continuous
https://www.myenglishpages.com/site_php_files/grammar-exercise-present-progressive.php
https://oudwww.bonhoeffer.nl/engels/brugklas/unit9/wb214.html
https://www.kico4u.de/english/uebungen/5klasse/presprofrag.htm
https://www.perfect-english-grammar.com/present-simple-present-continuous-1.html
https://elt.oup.com/student/solutions/preint/grammar/grammar_01_012e?cc=global&selLanguage=en
https://www.kico4u.de/english/uebungen/aktiv/preprog1.htm
There is/There are
https://www.englisch-hilfen.de/en/exercises/various/there_is_there_are.htm
https://www.kico4u.de/english/uebungen/5klasse/theisare1.htm
https://www.carmenlu.com/first/grammar/thereis1_2.htm
Comparatives
https://agendaweb.org/grammar/comparative-adjectives-exercises.html
https://www.perfect-english-grammar.com/comparative-adjectives-exercise-1.html
(irregulars) https://first-english.org/english_learning/english_year_2/comparison_adjectives/22_coparison_adjectives_irregular.htm
https://www.better-english.com/grammar/comp2.htm
Superlatives
https://agendaweb.org/grammar/comparison-superlative-exercises.html
Translation (los hay de diferentes niveles. Habrá frases cuyos tiempos verbales todavía no hemos visto. Haced las que podáis)
https://www.ejerciciodeingles.com/ejercicios-traduccion-frases-expresiones-frecuencia/
https://www.ejerciciodeingles.com/ejercicios-traduccion-frases-verbo-to-be/
https://www.curso-ingles.com/ejercicios-ingles/tradthere.php
https://es.slideshare.net/Luckygolucky/translation-booklet-frases-para-traduccion-inversa-espaol-ingls
Past continuous
https://www.perfect-english-grammar.com/past-continuous-exercise-1.html
https://www.myenglishpages.com/site_php_files/grammar-exercise-past-progressive.php
https://www.ego4u.com/en/cram-up/grammar/past-progressive
Past simple VS Past continuous
https://www.ego4u.com/en/cram-up/grammar/simpas-paspro
https://learnenglish.britishcouncil.org/es/quick-grammar/past-continuous-and-past-simple
https://www.perfect-english-grammar.com/past-simple-past-continuous-exercise-1.html
https://www.ecenglish.com/learnenglish/lessons/past-simple-vs-past-continuous
Present simple VS Present continuous
https://www.ego4u.com/en/cram-up/grammar/simpre-prepro
https://www.perfect-english-grammar.com/present-simple-present-continuous-1.html
https://elt.oup.com/student/solutions/preint/grammar/grammar_01_012e?cc=global&selLanguage=en
https://www.ecenglish.com/learnenglish/present-simple-and-present-continuous