There is no hard and fast rule as to which piece is placed on the top when working with these shapes, but it hat been found that distortion is less likely to occur when the outer curve is uppermost.

• 当缝合这两种类型的裁片时,就放在上面一层的裁片而言,是不难的且很快就能掌握,但发现缝至弯曲的凸出部位最凸出的部分时,不太容易使其缝合圆顺。