蛋白质的含氮量约为()。
A.6%
B.10%
C.16%
D.20%
E.26%
参考答案:C
Sichuan Province, ________ in southwest China and ________ an area of 485,000 kilometers with the largest population in China, is one of the largest and most inaccessible provinces in China.
A.located; covered
B.locating; covering
C.located; covering
D.locating; covered
社区中对1~3岁儿童补钙以预防佝偻病,这一方法属于
A.病例对照研究
B.现况研究
C.队列研究
D.社区干预试验
E.现场试验