Ostriches swallow sand and pebbles to help grind up food in their stomachs.

鸵鸟会大量吞咽沙子和卵石，以此来磨碎他们胃里的食物。

Millstones grind up cereals into powders.

石磨将谷物研成粉末。

In a pestle and mortar, grind up dried chillies, dried bay leaves and sea salt.

在一个石碾中，把干辣椒，月桂叶和盐碾碎。

We normally grind up a leaf or a root and average the information for all cells, but if sugar levels rise in one cell and drop in another, we would see no change in this average.

我们通常将植物的根和叶碾成粉末，然后平均所有细胞的成份，但是如果在单个细胞糖水平升高和降低，我们将从平均水平上是看不出来的。