网上特约商户证书的有效期为()年,逾期自动失效。
A、1
B、2
C、3
D、5
参考答案:B
Although he had taken a lot of medicine, his health _____poor.
A.prove
B.remained
C.maintain
D.lasted
番泻叶药材的主要化学成分是()
A.蒽醌类
B.挥发油类
C.黄酮类
D.靛蓝和靛玉红
E.皂苷类