求翻译！OG Verbal 2ND SC 76题

dennis2k

题目做对了，但句子表达的意思看着还是很模糊，求翻译！（已写成正确句子）
Under a provision of the Constitution that has never been applied, Congress is required to call a convention to consider possible amendments to the document when formally asked to do so by the legislatures of two-thirds of the states.