不能随便做某事英语怎么说

不能随便做某事英语可以说成 "You can't just do something without permission." 或者 "You can't do something without proper authorization." 这个表达源自于英语中有关许可或授权的概念。

例句：

You can't just take someone else's belongings without permission. 你不能拿别人的东西而不征得许可。
You can't enter the building without proper authorization. 没有适当的授权，你不能进入这座建筑物。
You can't just make decisions for others without consulting them first. 不经过咨询，你不能代替别人做决定。