If you went back to elementary school right now and started studying with the children, would you think their classes are difficult?
Adding numbers, learning the letters in English, learning to pronounce words... etc.
Absolutely not！！！
You can do all these things without thinking! They are just child's play for you.
如果你现在回到小学，开始和小孩子一起学习，你会觉得学习难吗？
基础数字，学习英文字母，学习发音单词等等对你来说特别容易的东西。
绝对不难！！！
你可以毫不犹豫地做所有的事情！他们只是对小孩子们有难度。
Child's play means an extremely simple task, something that is very easy to do.
You can use it to say :
Child's play 意味着一个非常简单的任务，非常容易的事情。有小儿科的意思。
你可以用它来说：
1. Something is really easy
做某件事真的很简单
Getting a new job should be child's play for someone with his skills.
对拥有他这样的技能的人，找份新工作不会有问题的
It is child's play for a good programmer to hack into a computer.
It's child's play for a chef to fry an egg
2. Something is NOT easy, and should be taken seriously.
某件事情很不容易，应该认真对待
Advertising to children isn't child's play!
Designing apps（软件） for kids is not as easy as it looks!
3。 To brag that something difficult is very easy for you:
为了吹牛那些一般很困难的事情对你来说很容易
为了看在电影里用child's play 的视频和实用图片，请进入我的公众号看看。
我是个巴基斯坦的在线老师，热爱语言，喜欢帮助大家轻松学英语