Grammar: exercises
Comparatives
http://esl.fis.edu/grammar/single/compare1.htm
Articles
https://www.anglaisfacile.com/exercices/exercice-anglais-1/exercice-anglais-111.php
http://www.anglissime.com/trainingdir/a-an-the.php
Present simple & present continuous
https://www.anglaisfacile.com/exercices/exercice-anglais-2/exercice-anglais-24156.php
Past tenses
https://www.anglaisfacile.com/exercices/exercice-anglais-2/exercice-anglais-5884.php
Present perfect & simple past
http://www.grammarbank.com/present-perfect-exercises.html
http://www.perfect-english-grammar.com/present-perfect-exercises.html
https://www.anglaisfacile.com/exercices/exercice-anglais-2/exercice-anglais-73643.php
Present perfect – Present perfect continuous :
https://www.anglaisfacile.com/exercices/exercice-anglais-2/exercice-anglais-28331.php
For/since
https://www.anglaisfacile.com/exercices/exercice-anglais-2/exercice-anglais-34639.php
Passive voice
https://www.ego4u.com/en/cram-up/grammar/passive
If clauses
https://www.anglaisfacile.com/exercices/exercice-anglais-2/exercice-anglais-44239.php
https://www.anglaisfacile.com/exercices/exercice-anglais-2/exercice-anglais-44296.php