Fighting in Vietnam was an experience that would haunt him for the rest of his life.

haunt 是动词，意思是"（不好的回忆或情感）长期困扰、萦绕"，常用来形容令人不安的记忆或经历像幽灵一样挥之不去。这个词来源于古英语，原指"鬼魂出没"，后来引申为"长期困扰"的比喻意义。