白芷的主要成分为
A．生物碱
B．香豆精类和挥发油
C．苷类
D．萜类
E．鞣质
参考答案：B
______ on his past mistakes, Ted realized that he had stayed around the wrong people.
A．To reflect
B．Reflecting
C．Reflected
D．Being reflected
—Would you like some coffee or tea?
—_____. Water is OK. [ ]
A. Both
B. Either
C. Neither
D. All
