具有活血止痛、行气解郁、凉血清心、利胆退黄功效的药物是（）。

A.丹参

B.川芎

C.郁金

D.益母草

E.玄参

____ by taking part in practice can the young people be toughened and hardened into steel

A．Still

B．Just

C．Only

D．Yet