These books【sell 】（卖）very well.Go and buy one before they're【sold】（卖）out.
第一个空：sell well 畅销 ,不用被动语态
第二个空：be sold out 被售完,用被动语态
句意是：这些书很畅销,在它们被卖完之前去买一本吧.能翻译一下吗哦