The front roll (active roll)realizes automatic track-propulsion;

前辊（活动辊）实现自动跟踪推进；

youdao

If you're on a witness protection program or you're sort of fugitive you probably don't want to sit on the front roll.

如果你在证人保护计划之内，或者是个逃犯级人物，就尽量不要坐在前排了。

youdao

When this happens uniformly across a large front, a roll cloud may form.

由于同时发生在一个面积广阔的锋面，于是就形成了这种卷云。

youdao

If you're on a witness protection program or you're sort of fugitive you probably don't want to sit on the front roll.

如果你在证人保护计划之内,或者是个逃犯级人物,就尽量不要坐在前排了

耶鲁公开课 - 心理学导论课程节选

So how many time do you think-- you all have a piece of paper in front you-- how many time do you think you need to roll over the piece of paper ? for the piece of paper to reach the moon?

你们认为需要折多少次-,你们面前都有一张纸-,你们认为需要将纸折叠多少次,才能碰到月亮？

哈佛公开课 - 幸福课课程节选

What you need to do is develop the idea, get the risk out up front, then roll the money in and develop the company.

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No longer do they abandon their patients once they roll out the front door.

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He had a little statue of Aubie on his desk. (Laughter.) He had his son, Ethan -- he and Ethan would roll the trees in front of the yard after a big win. (Laughter.) So this is a big day for him.

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