Where _____ you _____ from?[ ]
A. are, come
B. are, coming
C. do, come
D. do, coming
答案:C
WHO推荐12岁以下儿童日摄入碘的安全范围是
A.20~40μgB.40~60μgC.50~80μgD.50~100μgE.50~120μg
水陆环境的差异。