Tom is an American boy. _____ mother is a doctor. [ ]
A. Her
B. He's
C. His
D. Him
答案:C
咨询活动时,一位孕妇想了解,如果生活社区的水氟浓度很低(小于0.3mg/L)给孩子补充氟的问题。WHO专家委员会推荐,如生活社区的水氟浓度小于0.3mg/L。
开始补充氟滴剂的剂量是
A.0.02mg/d
B.0.23mg/d
C.0.25mg/d
D.0.30mg/d
E.0.33mg/d
氧化钙的化学式为()。
A.CaO
B.CAO
C.OCA
D.OCa