7. If the base edge length and the side edge length of a regular pyramid are equal, then the pyramid must not be ( ).
(A) Triangular pyramid
(B) Square pyramid
(C) Pentagonal pyramid
(D) Hexagonal pyramid
7. (D).

If the base edge length of a regular hexagonal pyramid is equal to the slant height, and since the base edge length is equal to the radius of the base, then in the right triangle formed by the height of the hexagonal pyramid, the radius of the base, and the slant height, the slant height and the radius of the base are equal (i.e., the hypotenuse is equal to one of the legs), which is impossible.