"Difficult to distinguish" 可以用英语表示为 "hard to tell apart" 或者 "hard to distinguish."
这个表达的来源可能源于人类的视觉系统有时候难以辨别两个相似的物体。
下面是一些英文例句，其中文翻译仅供参考：
It's hard to tell the difference between the two types of apples. They look almost identical. (很难区分这两种苹果。它们看起来几乎一模一样。)
The twins are so apke that it's almost impossible to distinguish them. (这对双胞胎长得如此相似，几乎不可能辨别出来。)
The forgery was so well done that it was hard to distinguish it from the original. (伪造的作品做得非常好，很难区分出来是伪造的。)
这个表达的来源可能源于人类的视觉系统有时候难以辨别两个相似的物体。
下面是一些英文例句，其中文翻译仅供参考：
It's hard to tell the difference between the two types of apples. They look almost identical. (很难区分这两种苹果。它们看起来几乎一模一样。)
The twins are so apke that it's almost impossible to distinguish them. (这对双胞胎长得如此相似，几乎不可能辨别出来。)
The forgery was so well done that it was hard to distinguish it from the original. (伪造的作品做得非常好，很难区分出来是伪造的。)