Prepositions of Place - Practice

http://www.perfect-english-grammar.com/prepositions-of-place-exercise-1.html

http://speakspeak.com/english-grammar-exercises/intermediate/prepositions-of-place-at-in-on

Question Forms - Practice

http://www.grammar.cl/Games/Question_Words.htm

http://www.grammar.cl/Games/Question_Words_2.htm

http://www.grammar.cl/exercises/question-words.pdf

http://www.myenglishpages.com/site_php_files/grammar-exercise-wh-questions.php

Simple Past, Past Continuous, Used To- Practice

http://www.grammar.cl/Games/Past_Irregular_Verbs.htm

http://www.perfect-english-grammar.com/past-simple-exercise-7.html

http://www.perfect-english-grammar.com/past-simple-exercise-8.html

http://www.perfect-english-grammar.com/used-to-exercise-1.html

http://www.perfect-english-grammar.com/used-to-exercise-2.html

http://www.perfect-english-grammar.com/used-to-exercise-3.html

Present Simple and Present Continuous - Practice

http://www.really-learn-english.com/simple-present-exercises.html#05

http://www.grammar.cl/Games/Simple_Present_Tense.htm

http://www.really-learn-english.com/present-progressive-exercises.html#01

http://www.really-learn-english.com/present-progressive-exercises.html#04

http://www.englishpage.com/verbpage/verbs1.htm

http://www.englishpage.com/verbpage/verbs2.htm

http://www.grammar.cl/Games/Present_vs_Progressive.htm

Adverbs of Frequency - Practice

http://www.englisch-hilfen.de/en/exercises/adjectives_adverbs/adverbs_of_frequency.htm

https://elt.oup.com/student/solutions/elementary/grammar/grammar_02_012e?cc=ar&selLanguage=en

http://www.grammar.cl/Games/Adverbs_of_Frequency.htm

Prepositions of time - Practice

http://www.englishpage.com/prepositions/time_prepositions_1.htm

http://www.englishpage.com/prepositions/time_prepositions_2.htm

http://www.englishexercises.org/makeagame/viewgame.asp?id=5278