VOA慢速英语:英国疫苗大臣称全球约有4000种新冠病毒变种

variant – n. different in some way from others of the same kind

mutate – v. to cause (a gene) to change and create an unusual characteristic in a plant or animal

immunity – n. to be protected against catching a disease

library – n. a place where books are available to the public

respond – v. to answer or to reply

challenge – n. to test the ability, skill, or strength of (someone or something)

advantage – n. something (such as a good position or condition) that helps to make someone or something better or more likely to succeed than other