下列哪一个强心苷在静脉给药时起效最快
A．毛花苷丙
B．洋地黄毒苷
C．铃兰毒苷
D．高地辛
E．毒毛旋花子苷K
参考答案：E
— Tom is never late for work. Why is he absent today?
— Something _____ to him. [ ]
A. must happen
B. should have happened
C. could have happened
D. must have happened
地月系的质心不是（）。
