A.每隔10~15m B.每隔15~20m C.每隔20~25m
A.大面朝上,相互對(duì)齊 B.大面朝下,相互錯(cuò)開 C.大面朝下,相互對(duì)齊
A.規(guī)定的時(shí)間,2h B.24h,2h C.8h,4h