VOA慢速英语:华盛顿特区的学校在健康危机期间进行实验

virtual –adj. existing or taking place on computers or on the internet

(labor) union –n. an organization of workers formed to protect the rights and interests of its members

essential workers –n. workers who are required to work during a business closure to meet operational requirements

advocate –n. a person who argues for or supports a cause or policy

fountain –n. a device that sends out a stream of water (for drinking)

awareness –n. knowledge of something