Błędnie: After she had been drafted as a military doctor, she cut off many appendices. Poprawnie: After she had been drafted as a military doctor, she cut off many appendixes.
Rzeczownik ‘appendix’ oznacza albo „wyrostek robaczkowy” (wtedy liczba mnoga to ‘appendixes’) albo „dodatek”, „suplement do książki” (wtedy liczba mnoga brzmi albo ‘appendices’, albo ‘appendixes’).