用an，例如：

1. She cracked an egg into the pan.她往鍋里打了一個雞蛋。

2.Crack an egg and separate the yolk immediately.打一個雞蛋，然后立刻將蛋黃分離出來。3.Add an egg yolk to make the mixture bind.加個蛋黃使混合料凝結(jié)在一起。4.Suppose someone gave you an egg and asked you to describe exactly what was inside.假設(shè)有人給了你一枚雞蛋并要你準(zhǔn)確描述雞蛋里面有什么。