Continuous Double Auction (CDA) is a popular market institution for real-world trading of commodities as well as electronic marketplaces. In this paper, we present the design and analysis of a new strategy for buyer and seller agents participating in agent-based CDAs. We consider a series of CDAs, the participants of which have similar behaviors in any two successive CDAs. These strategies employ heuristic rules and reasoning mechanism based on a two-level adaptive bid-determination method, including long-term and short-term attitudes. Agents adopting these strategies dynamically adjust their behaviors in response to the changes of the supply-demand relation in the market. Experiments show that agents adopting these strategies outperform other strategies reported in the literature.