China market in recent years, with the villas, penthouse rooms, double deck houses, roof slope, oxygen, which go downstairs through the prevalence of stairs began a sharp increase in frequency.

• 近年来，随着别墅、复式房、夹层屋、斜坡屋顶、跃层、上下楼打通的盛行，楼梯出现的频率开始急剧增高。