Hxen.com's tips：Every day persisted can learn English well!-->■Learn English Everyday■
immunity – n. the ability of a person or creature to resist an infection by the action of antibodies or white blood cells
amnesia - n. a condition in which a person is unable to remember things because of brain injury, shock, or disease
encounter – v. to come into contact with or face something
outbreak – n. the sudden violent start of something
upsurge – n. a sudden increase or rise — usually + in or of
deleterious - adj. damaging or harmful
specific – adj. clearly defined
