Are they your books?还是Are these your books?为什么?

Are they your books?还是Are these your books?为什么?

Are these your books?They 不能指物,用these指代这些书

these
习惯这么使用,英语没那么多原因,语言是说出来的

Are these your books?

都可以吧应该

Are they your book?是不合适滴 如果把这句话变成陈述句就是
They books are yours.没有这么说的 呵呵