"away, backwards," c. 1200, Northern English and Scottish dialectal fra, Midlands dialect fro, from Old Norse fra "from," from Proto-Germanic *fra "forward, away from," from PIE *pro- (see pro-). The Norse word is equivalent to Old English fram, thus fro is a doublet of from.
权威例句
1. She stood up and began to pace to and fro.
她站起身,开始来回踱步。
2. The boat was rocking gently to and fro in the water.
小船在水中轻轻地来回摇荡。
3. They travel to and fro between London and Paris.
他们奔走于伦敦和巴黎之间.
4. The girl's pigtails swing to and fro as she runs.