既能健脾又伯祛风湿的药物是（）。
A.厚朴
B.苍术
C.独活
D.羌活
E.防风
参考答案：B
With more forests being destroyed, huge quantities of good earth ___________ each year.
A．is washing away
B．is being washed away
C．are washing away
D．are being washed away
简述保证的含义和特征。
