当归可用于治疗（）
A．血虚肠燥便秘
B．食积腹痛便秘
C．阴虚肠燥便秘
D．实热积滞便秘
E．津枯肠燥便秘
参考答案：A
_____ she knew her father was safe _____ crying. [ ]
A. Because; so she stopped
B. When; did she stop
C. Until; she didn't stop
D. Not until; did she stop
半数致死剂量(LD50)是指
A．引起—群个体50%死亡的剂量
B．引起50%的人产生毒作用的剂量
C．消毒剂杀灭一半致病菌的剂量
D．杀虫剂杀死一半有害昆虫的剂量
E．致死剂量一半
