莫明其妙的

例句：

1. 1. The story behind the painting was so mysterious that even experts couldn't explain it.
   这幅画背后的故事如此神秘，以至于即使是专家也无法解释。
2. 2. The reason for her sudden departure was quite unexplainable.
   她突然离开的原因相当难以解释。
3. 3. The solution to this problem is quite a mystery.
   解决这个问题的方法相当神秘。