This paper has studied the theory and mathematic model of twisting machine's to-and-fro guiding-yarn and put forward a new way of servo to-and-fro guiding-yarn system and realized it.

本文研究了捻线机往复导纱系统原理及其数学模型，提出了一种新的伺服往复导纱系统以及实现该系统原理的方法。

youdao

I paced the floor to and fro with heavy strides, as if excited to fury by the observations of the men -- but the noise steadily increased.

VOA: special.2009.02.02

Let me go and put that up-- it'll be tiring but let me go to and fro a bit.

让我回到讲台上记一下,虽然这样很累但是我多走几个来回吧

耶鲁公开课 - 博弈论课程节选

Paisley took that line that it was a disgrace, it would be a disgrace giving way to terrorism, to abandon this historic march, just because of the trouble made by the Republicans, the IRA in Londonderry, and in the to and fro and the arguments about this, Paisley demanded that if there were to be a march, then the quid pro quo must be the introduction of internment.

BBC: Transcripts: Lord Carver - Chief of the General Staff

As Thailand and others pressure Vientiane to open up, Hanoi leans on it to keep the communist faith - and Laos lurches to and fro along the road to reform.

CNN: CAUGHT IN THE MIDDLE

And parking should become a doddle: the sidestick would eliminate the need to wrestle the steering wheel to and fro.

ECONOMIST: Drive by wire