child's play 小儿科，非常简单的工作，轻而易举的事

　　Come on, this is like child's play. Even a baby can do this.

　　啊，这太简单了，一个baby都能搞定。

　　I finished the test very quickly. It was child's play!

　　我很快就完成了测试，太小儿科了。

　　疯狂练习吧！