The connection unit is the most common part of the change in the reproduction unit, and the reproduction unit does not need to emphasize the contradiction between the main and the sub-sections as in the presentation unit, but balances the unstable state of the non-main tone for a long time. Compensation, this unstable state happens to start from the connection portion in the presentation portion, and the connection portion in the reproduction portion requires almost no modification. This change is unique in Beethoven’s piano sonata style, with different techniques, reflecting Beethoven’s skilled writing skills and personal style.