从黄芩中提取黄芩苷多采用的提取方法是
A.水浸泡酸沉淀 B.碱水提取酸沉淀 C.甲醇提取酸沉淀D.乙醇提取酸沉淀 E.丙酮提取酸沉淀
参考答案:B
— Is Paul playing both soccer and tennis for the school?
— He ______. But now he has given up playing tennis.
A.is
B.has
C.was
D.had
击实试验曲线上最高点对应的横坐标的数为()
A.最大干密度
B.最优含水率
C.干密度
D.含水率