VOA慢速英语:US Security Agency Contractor Arrested

contractor – n. a person who is hired to perform work or to provide goods at a certain price or within a certain time​

classified – adj. kept secret from all but a few people in the government

clearance – n. an official decision saying that someone has permission to do something

grave – adj. very serious; requiring or causing serious thought or concern

device – n. an object, machine or piece of equipment that has been made for some special purpose

surveillance – n. the act of carefully watching someone or something especially in order to prevent or detect a crime

espionage – n. the things that are done to find out secrets from enemies or competitors; the activity of spying