suspect 和 doubt 的区别

今天和美国人聊天时无意中讨论到 suspect 和 doubt 的区别。两个词中文都翻译成“怀疑”，但是后面加“that”从句的时候意思相反：suspect that... 表示认为某件事会发生；doubt that... 表示认为这件事不会发生。下面两个例句可以对比一下：
Though all other people believed in him, she suspected that he was lying.
I doubt that he is lying; he sounds very honest.