颅缝闭合的时间为
A.出生时
B.6~8周
C.3~4个月
D.8~10个月
E.1~1.5岁
参考答案:C
以下哪项不是牙体修复材料应具备的性能的是()
A.能承受较大的咀嚼压力,扭力和冲击力,能耐磨
B.对机体无毒,对牙髓、粘膜无激惹性
C.不使牙齿变色
D.化学性能稳定,在唾液中不溶解,不变性
E.能与洞壁密合,必要时易去除
On-scene communications will normally take place between().
A.ship in distress and assisting units
B.NCS and RCC
C.RCCs and “on-scene commander” or “coordinator surface search”
D.ship in distress and coast station