The two principaltrading systems in security markets are competing system and market making system.
证券市场的两种主要交易机制是竞价方式和做市商制度。
2
This has often resulted in very confusing standard trading conditions where the two contradictory roles and kinds of responsibility-of the agent and of the principal-are set out.
这往往造成非常混乱的情况，即是很容易导致两种不同角色及责任的混淆—代理和合同当事人。
3
Agent as the trading assistant makes the ability and action of principal extended, when the agent's act can be able to repeat in time and expand in space.