Who would have thought he'd get sore-eyed from writing too much instead of watching TV?

who 是疑问代词，意思是"谁"，用于询问或引出疑问句。 would 是情态动词 will 的过去式，在这里表示假设或推测的语气。 have 是助动词，与过去分词 thought 构成现在完成时，表示"已经"。 thought 是动词 think 的过去分词，意思是"认为、思考"。 who would have thought 是一个固定表达，字面意思是"谁会想到"，用来表示对意外情况的惊讶或感叹。