Who would have thought that it would rain in the desert?

who 是疑问代词，表示"谁"，用于询问或指代某个人。 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 构成完成时态，表示"已经"或"曾经"。 thought 是动词 think 的过去分词，意思是"想、认为"。 who would have thought 是一个固定表达，表示"谁会想到"或"谁能预料到"，用来表达对意外情况的惊讶。