belly

小宝宝开心地露出圆圆的肚子。

The baby happily showed his round ___belly.

这只猫的腹部有一块白色的斑点。

There is a white spot on the cat's ___belly.

青蛙腹部的颜色通常比背部浅。

The frog's ___belly is usually lighter in color than its back.