to and fro什么意思解释？

to and fro的音标：to and fro的英式发音音标为：[tu: ænd frəʊ]to and fro的美式发音音标为：[tu ənd fro]...

She stood up and began to pace to and fro.她站起身，开始来回踱步。The boat was rocking gently to and fro in the water.小船在水中轻轻地来回摇荡。They travel to and fro between London and Paris.他们奔走于伦敦和巴黎之间....