yo-yo      
 noun [ C ]  trademark uk/ˈjəʊ.jəʊ/ us/ˈjoʊ.joʊ/  yo-yos
 游游拉线盘,悠悠球(一种玩具)
a toy consisting of a circular object that can be made to go up and down a long piece of string to which it is tied
 yo-yo       
 adjective uk/ˈjəʊ.jəʊ/ us/ˈjoʊ.joʊ/
 形容摇摆不定、时常反复的事物
used to refer to something that moves up and down quickly, or something that changes repeatedly between one level and another
  yo-yo dieting 间歇性节食 
 yo-yo       
verb [ I ] uk/ˈjəʊ.jəʊ/ us/ˈjoʊ.joʊ/
 上下快速移动;在不同层面间不停变化
to move up and down quickly, or to change repeatedly between one level and another
  She said that her weight had yo-yoed over the years. 她说她的体重多年来一直不停摇摆变化。