Don't shout at him. He is just a _____ child.[ ]

A. six years old            

B. six-years-old

C. six-year-old              

D. six-years-old

非织造类滤布是将羊毛或合成短纤维做无规则地密集排列、可以添加或不添加权脂粘结剂、经过压实形成一个纤维层粘结在一起、外表像不得疏松集合物。