1. Never trouble trouble till trouble troubles you. 麻烦没来找你，就别去自找麻烦。 第一、四个trouble是动词，第二、三个trouble是名词。 2. I think that that that that that student wrote on the blackboard was wrong. 我认为那个学生写在黑板上的那个“that”是错误的。 第一个that是连词，引起宾语从句；第二、五个that是指示代词“那个”；第三个that在这儿相当于名词；第四个that是关系代词，引起定语从句。 3. I know....