1988 AMC 12 第 23 题

The edge of length $7$ belongs to two triangular faces

In either face containing that edge, the other two edge lengths must differ by less than $7$

For a face containing the edge $7,$ its other two sides must differ by less than $7.$ Among the remaining lengths, the only disjoint pairs with this property are $(13,18)$ and $(36,41),$ so edge $27$ is opposite edge $7.$ With $AB=41,$ the two possible placements of these pairs can be checked by the triangle inequalities; the placement making the edge opposite $AB$ equal to $18$ fails, while the valid placement has $CD=13.$

Thus the correct answer is B.