PET Saturdays

Questions with prepositions at the end

https://www.tolearnenglish.com/exercises/exercise-english-2/exercise-english-117985.php

https://www.test-english.com/grammar-points/a2/subject-questions-questions-preposition/

https://www.ecenglish.com/learnenglish/lessons/10-prepositions-questions

Modals of obligation

https://www.perfect-english-grammar.com/modal-verbs-of-obligation-exercise-1.html

http://www.autoenglish.org/modalverbs/ModalsObligation.htm

https://www.english-at-home.com/grammar-modals-obligation/