底子的英文：
grounding

Will you get me a quite plain parasol?
你替我买把小阳伞行吗？要素底子的。

Too many student nurses flunk out of the course because their math is weak.
许许多多学护士的学生因为数学底子太差考试不及格而退学。

on solid ground
在稳固的基础上

Their ship was grounded.
他们的船搁浅了。

The ground has thawed.
地面解冻了。

The beans are then ground and packaged for sale as ground coffee.
然后那些咖啡豆被磨碎，包装好作为咖啡粉出售。

He was lying flat on the ground.
他平躺在地上。