At the back of the mouth it has teeth with flat tops for grinding its food.

嘴后面的牙, 顶上是平的, 用来把食物磨碎。

In a creek or river, stepping-stones are rocks with flat tops that sit above the water line.

在小溪或河流中，垫脚石是指有露出水面的平坦顶部的岩石。

Letters with rounded tops have to be slightly taller than letters with flat tops in order for them to appear the same size.

带有圆形顶部的字母必须比带有平顶的字母稍高，以便它们看起来大小相同。

At the back of its mouth the sheep has six teeth with flat tops on each side of each jaw. These are called grinders.

绵羊嘴的后面，上腭和下腭的两边，各有六颗牙齿，牙齿的顶端是平的，叫磨牙或者臼齿。