许多国家十分重视海水资源的综合利用。下列物质不需要化学变化就能够从海水中获得的是[ ]
A.氯、溴、碘
B.钠、镁、铝
C.烧碱、氢气
D.食盐、淡水
答案:D
______ with new scientific farming methods, they have been able to use less farmland thanin the past.
A.Equipped
B.Having equipped
C.To be equipped
D.Equipping
由创伤牙合造成的隐裂在治疗时应首先
A.开髓失活
B.全冠修复
C.备洞充填
D.降低咬合
E.拔除患牙