普鲁烟酰胺的主要作用机制是()
A.抑制钠内流
B.抑制钙内流
C.抑制钾内流
D.阻断β受体
E.延长动作电位时间
参考答案:A
- When did the computer crash?
- This morning, while I ______ the reading materials downloaded from some websites.[ ]
A. have sorted
B. was sorting
C. am sorting
D. had sorted
我国生活饮用水水质标准规定,水中的细菌总数和总大肠埃希菌群数不得超过()
A.100个/ml,3个/L
B.100个/ml,10个/L
C.200个/ml,1个/L
D.200个/ml,3个/L
E.300个/ml,1个/L