药物体内血药浓度消除一半所需要的时间，称为（）
A．生物利用度
B．绝对生物利用度
C．相对生物利用度
D．溶出度
E．生物半衰期
参考答案：E
—________ didn't you finish your homework, Jenny?
—Because my mother was ill. I had to take care of her. [ ]
A. Why
B. When
C. What
D. Where
—When is your first class?
—It’s at 8:20 am.
A．What’s the time
B．What time
C．Where
D．Why
