easier said than done 说时容易做时难；说起来容易，做起来难

【例句】
Often that is easier said than done.
往往说起来容易做起来难。

Of course, this is all a lot easier said than done, and a sophisticated computer AI will punish you for tactical errors.
当然，说起来容易做起来难。一个狡猾的AI会捕捉并惩罚您的每一个战术错误。