专业解读：A seesaw (also known as a teeter-totter or teeter board) is a long,narrow board pivoted in the middle so that,as one end goes up,the other goes down.
词汇起源：According to linguist Peter Trudgill,the term originates from the Norfolk language word tittermatorter.
A "teeter-totter" may also refer to a two-person swing on aswing seat,on which two children sit facing each other and the teeter-totter swings back and forth in a pendulummotion.
Both teeter-totter (from teeter,as in to teeter on the edge) and seesaw (from the verb saw) demonstrate the linguistic process called reduplication,where a word or syllable is doubled,often with a different vowel.Reduplication is typical of words that indicate repeated activity,such as riding up and down on a seesaw.
言简意赅：看见了,又下去了,循环往复~