没有谁，没有哪个nobody; nothing

• 莫不欣喜。

  Not one person was unhappy.

无not

• 世界上最大的骗局，莫过于此

  nothing beats the biggest swindle in the world

不要don't

• 莫哭。

  Don't cry.

• 请莫见怪。

  Please don't take offence.

• 请你莫去为是。

  Please don't go. It's not right.

表示揣测或反问particle to indicate a guess or a rhetorical question