A user-friendly query modeling tool and method, for representing, creating, modifying and modeling a query language statement for use in retrieving data from a database. The laptop computer is securable with the security devices when the laptop computer is in the open position. The charging filter has plural through holes by forming a fibrous electret filter medium in a pleat shape. The first and second walls become closer as they extend from the channel base, such that the first circumferential edge overlaps the second circumferential edge in a longitudinal direction of the grommet. The immunoassay of the invention has advantages that it has high specificity and is simple and low in cost, and with respect to the antibodies used, insofar as one of the immobilized antibody and the free antibody has high specificity for the objective antigen of determination, the other antibody does not need to have strict specificity and may have some cross-reactivity.