提取生物碱、苷类等成分,宜选用乙醇的浓度一般是()
A.90%以上
B.70%~90%
C.50%~70%
D.40%~50%
E.20%~30%
参考答案:C
I refused his request, _________ that it was impossible to do it. [ ]
A. believed
B. to believe
C. convinced
D. to convince
()是随身护卫分析评估中可以进行量化的方法
A、德尔菲法
B、定量分析法
C、头脑风暴法
D、主观概率法