VOA慢速英语:美国教师短缺是一个比想象中更大的问题

previous - adj. existing or happening before the present time

average - adj. a number that is calculated by adding quantities together and then dividing the total by the number of quantities

background - n. the experiences, knowledge, education, etc., in a person's past

expense - n. the amount of money that is needed to pay for or buy something

superintendent - n. a person who directs or manages a place, department, organization, etc.

factor - n. something that helps produce or influence a result

maximum - adj. greatest possible in amount or degree

recruit - v. to find suitable people and get them to join a company, an organization, the armed forces, etc.

retain - v. to keep (someone) in a position, job, etc.