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doorbell – n. a device which visitors can ring to announce their arrival
vision – n. the state of being able to see
surveillance – n. close observation
digital – adj. related to the use of computer technology
match – v. to make equal in quality or strength;
discount – n. a price reduction
analyst – n. someone who works as an observer
burglary – n. stealing; robbery
data – n. facts and other information collected together for study
opportunity – n. a chance or possibility
