VOA慢速英语:iPhone Sales Fall, Ending Apple's Record Growth

units – n. an individual item of one of the products that a company makes and sells

margin – n. an extra amount of something (such as time or space) that can be used if it is needed

decade – n. a period of 10 years

revolutionary – adj. causing or relating to a great or complete change

content – adj. pleased and satisfied : not needing more

regularly – adv. on a consistent basis, very often