VOA慢速英语:2017年谷歌热搜排行榜

stream - v. to transmit or receive something over the internet

rotate - v. to move or turn in a circle

ball bearing - n. a part of a machine in which another part (such as a metal pole) turns easily

attention deficit hyperactivity disorder - medical terms - is a disorder marked by an ongoing pattern of inattention and/or extreme activity that interferes with functioning or development