All these changes will lead to ________ strong and powerful China, ________country that can surprise and enrich our planet.

A．a; a

B．the; a

C．the; the

D．a; the

钩藤所含的主要化学成分是( )

A．生物碱类

B．黄酮类

C．蒽醌类

D．甾醇类

E．挥发油类