Level 10 Teens Unit 1

     Verbs + to or ing

     https://www.englishclub.com/grammar/verbs-m_infinitive-ing_quiz.htm

     http://www.mansioningles.com/gram57_ej1.htm

     http://www.mansioningles.com/gram57_ej2.htm

     Prepositions + ing

     https://www.ego4u.com/en/cram-up/grammar/infinitive-gerund/exercises?20

     http://www.vitutor.com/gramatica_inglesa/verb_tense/ing_ej3.html

     https://englishgrammarsecrets.com/the-ing-form/grammar/

     verb + gerund or infinitive

     http://www.englishpage.com/gerunds/gerunds_infinitives_1.htm

     http://www.englishpage.com/gerunds/gerunds_infinitives_2.htm

     http://www.englishpage.com/gerunds/gerunds_infinitives_12.htm