This paper shows how to provide adaptable query evaluation using QBF, a Query Broker Framework that provides a set of tools facilitating the design and implementation of query function in data-intensive distributed applications. The framework allows the use of multiple mechanisms to adaptively evaluate queries according to application requirements and its execution context. The smallest query evaluation unit built on the framework is called a Query Broker. Query brokers can be organized in hierarchies for evaluating distributed queries. This paper concentrates on the adaptability of query brokers so as to illustrate query processing strategies supported by QBF.