2001-01-13 need help

guandream

13. In geometry, an ellipse may be defined as

   the locus of all points -------distances from

   two fixed points is constant.

(A) which as the sum of

   (B) of the sum which

   (C) whose sum of whose

   (D) whose sum that the

seinfeld0923

前人有过讨论，请搜索．

zhoushao

看这http://forum.chasedream.com/dispbbs.asp?BoardID=58&ID=71063