past simple vs present perfect https://www.ego4u.com/en/cram-up/grammar/simpas-preper/exercises?ex05 https://www.ego4u.com/en/cram-up/grammar/simpas-preper/exercises?ex07 https://www.ego4u.com/en/cram-up/grammar/simpas-preper/exercises?ex08
present perfect simple vs present perfect continuous https://www.ego4u.com/en/cram-up/grammar/prepersim-preperpro
present perfect: simple and continuous http://learnenglishteens.britishcouncil.org/grammar-vocabulary/grammar-videos/present-perfect-simple-and-continuous