Mr. Mindon saw a letter crushed into a small ball on the floor.

VOA: special.2009.01.31

And then we let the ball develop into a fully grown inner ear.

接下来，我们让泡囊发育成一个成熟的内耳。

斯坦福公开课 - 7个颠覆你思想的演讲课程节选

People form containers by pressing a ball of clay into a given shape.

VOA: special.2009.09.09

Mister Mindon saw a letter crushed into a small ball on the floor.

VOA: special.2010.05.29

a chance to throw the ball into the basket.

VOA: special.2011.03.25