Hxen.com's tips：Every day persisted can learn English well!-->■Learn English Everyday■
antibody – medical n. a substance produced by the body to fight disease
principle – n. a basic truth or theory : an idea that forms the basis of something : a law or fact of nature that explains how something works or why something happens
mutate – v. to cause (a gene) to change and create an unusual characteristic in a plant or animal : to cause mutation in (a gene)
pandemic – n. occurring over a wide geographic area and affecting an exceptionally high proportion of the population
