1N-COUNT (正式演出前的最后)彩排 The dress rehearsal of a play, opera, or show is the final rehearsal before it is performed, in which the performers wear their costumes and the lights and scenery are all used as they will be in the performance. (正式演出前的最后)彩排
2N-COUNT (事件的)预演,彩排 You can describe an event as a dress rehearsal for a later, more important event when it indicates how the later event will be. (事件的)预演,彩排
These elections, you could almost say, are a dress rehearsal for the real elections. [+ for]