单项选择题中药分析中最常用的提取方法是（ ） A、溶剂提取法 B、煎煮法 C、升华法 D、超临界流体萃取
单项选择题P: approach N-TE leaving FL90 for FL70.C: N-TE continue down to 4000ft transition level 50 QNH 998 At which level should the pilot change altimeter setting to QNHA.FL90B.FL70C.FL50D.FL40
