Silent Letters

https://www.myenglishteacher.eu/blog/list-of-words-with-silent-letters-in-english/

https://7esl.com/silent-letters/

/s-z/

https://academialatin.com/ingles/reglas-s-z/

RELATIVE CLAUSES.

https://www.ego4u.com/en/cram-up/grammar/relative-clauses/exercises?07

https://www.perfect-english-grammar.com/relative-clauses-exercise-4.html

https://www.examenglish.com/grammar/d_relative_clauses.htm

https://www.perfect-english-grammar.com/relative-clause-exercises.html

https://agendaweb.org/grammar/relative-clauses-english-exercises.html