During the presentation, his mind went blank and he lost his train of thought.

went 是动词 go 的过去式，表示"去、变得"的状态变化。 blank 是形容词，意思是"空白的、没有内容的"，形容大脑突然失去思考能力的状态。 went blank 是一个固定搭配，表示"突然变得一片空白"，通常用来形容大脑突然无法思考或记忆暂时缺失的状态。