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recur – v. to happen or appear again
retain – v. to continue to hold (something, such as heat or moisture) as time passes
paralysis – n. medical : a condition in which you are unable to move or feel all or part of your body
poliomyelitis – medical n. : polio
chemotherapy – medical n. : the use of chemicals to treat or control a disease (such as cancer)
modify – v. to change some parts of (something) while not changing other parts
