为什么很难制造疫苗和增加供应

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ingredient –n. one of the materials used to make something like food or medicine

soup -–n. food made by cooking vegetables or meat in liquid

spike –n. a long thin structure that sticks out from a surface

dose –n. the amount of medicine needed to treat a sickness

sneak –v. to take or bring in a secret or hidden way

variability –n. something's ability to change or be changed

facility –n. a center including buildings or equipment that are built for a specific purpose

capacity –n. the ability to do something such as produce a product or medicine