《高层民用建筑设计防火规范》规定,高层建筑电缆井、管道井与房间、走道等相连通的孔洞,其空隙应采用()材料填塞密实
A.难燃烧
B.不燃烧
C.易燃烧
D.阻燃处理
参考答案:B
Children should be encouraged to help their parents,which________helps them to learn how to
cooperate and share. [ ]
A. in return
B. in addition
C. in brief
D. in turn
下列机床传动方式中,( )可以实现无级调速的运动。
A.齿轮传动
B.电子传动
C.气压传动
D.液压传动
E.蜗轮蜗杆传动