on earth: 究竟
Who on earth told you that?
究竟是谁告诉你的？

lose your mind: 发狂，发疯
Have you completely lost your mind?
你真的彻底疯了?
Uther the Lightbringer: Treason? Have you lost your mind, Arthas?
乌瑟尔光明使者:叛国?你是不是疯了,阿尔赛斯?

keep from: 阻止，防止
Hearing the words, he couldn't keep from laughing.
听了这话，他不由得笑了起来。
He was argumentative, loud and just plain rude. We bit our tongues the entire weekend to keep from telling him where to go!
他好争论，大嗓门并且毫无礼貌。整个周末我们强忍住未向他下逐客令。