VOA慢速英语:Report Says Americans Less Happy

poll – n. an activity in which several or many people are asked a question or a series of questions in order to get information about what most people think about something

compile – v. to put together in a publication or collection

survey – n. an activity in which many people are asked a question or a series of questions in order to gather information about what most people do or think about something

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