使用苯甲酸钠的最适pH为()
A.pH=4
B.pH<4
C.pH>4
D.pH>7
E.pH=7
参考答案:B
解析:
苯甲酸钠要想发挥最大的防腐效果其最适pH值应该在4以下.
They planned to go to Guangzhou to watch the Asian Games, but because of their daughter's unexpected
illness they had to stay at home ____. [ ]
A. otherwise
B. anyhow
C. however
D. instead
铝锭内在质量等级生产指标是怎样控制的?