按经济用途分类，绵羊分为哪些类？
参考答案：
粗毛羊，肉脂羊，裘皮羊，羔皮羊，细毛羊，半细毛羊
隋唐时期的时代特点（）
Could you please ________ such a thing again? [ ]
A. not to do
B. don't do
C. not doing
D. not do
