With a roll ball rocking arm and balance tray. It is a smart design and convenient to be installed quickly.

备有流滚珠式驻持摇臂及平衡托架，设计巧妙，安装简便，快捷。

youdao

If you roll a ball up a slop, it will roll down again.

如果你把球滚上斜坡，它还会滚下来。

《新英汉大辞典》

Some animals roll themselves into a ball for protection.

有些动物蜷缩成一团以保护自己。

《牛津词典》

Brunt latched on to a misplaced back-pass by James Chambers to beat goalkeeper Sullivan to the ball and the Northern Irishman was able to simply roll the ball into the empty net for his 13th goal of the season and the Baggies 100th goal in all competitions this campaign.

BBC: Doncaster 2-3 West Brom

Nikica Jelavic then ran on to a woeful back-pass from Richie Towell to round Graeme Smith and roll the ball home.

BBC: Hibernian 0-2 Rangers

The trio carved open the Motherwell defence, setting up Stewart to roll the ball home after his late run into the box.

BBC: Hearts 3-2 Motherwell