根据首字母提示完成下列短文。

      Long ago, the dog f_________ a big and h_________ bone. He wanted to c_________ it t_________ the

forest, but he stopped at a l_________. Because he saw a dog i_________ the water w_________ a bone. He

barked a_________ the dog and lost his b_________. Finally he felt s_________, but he learned a lesson.

下列属于证券经纪商应发挥的作用的是( )。

A．提供证券资产管理

B．提高证券投资的收益

C．提供信息服务

D．防止股价波动