It's a piece of cake.
小菜一碟啦。

Scene
Laura: Are you sure you can pass the MBA exam?
Alile: Absolutely. It's a piece of cake.

Notes
呵呵， 你是否也把这句话理解为“这是一块蛋糕”呢？ 其实从对话情景来看就可以猜出它并不是在讲蛋糕。其真正意思是“小事一桩，轻而易举的事情”。^_^

Exercises
现在来看看这个句子怎么说：
我觉得学英语对Steven来说简直是小菜一碟。