定语从句限定词Ingeometry,anellipsemaybedefinedasthelocusofallpointsthesumofwhosedistancesfromtwofixedpointsisconstant.请问此处为什么要用whose,这个词一般不是修饰人的吗?thesumof在句中作什么成

Question

定语从句限定词
In geometry, an ellipse may be defined as the locus of all points the sum of whose
distances from two fixed points is constant.请问此处为什么要用whose,这个词一般不是修饰人的吗?the sum of 在句中作什么成分?为什么要放到whose之前?

Answer 1

1、Whose 用作关系代词时,既是who 的所有格形式,也是 which 的所有格形式,因此既能指人也能指物.如：
* I saw a girl whose beauty took my breath away.我看见一个美得让我十分惊异的女孩子 (whose beauty = the beauty of whom【即 the beauty of the girl】)
* This is the pen whose point is broken.这就是笔尖断了的那枝笔.(whose point = the point of which【即 the point of the pen】)
同理,下面的情况同样是互等的：
* the book of whom = whose book（先行词说的那个人的书）
* the cover of which = whose cover（先行词说的那个东西的封面）
2、定语从句中关系词的用法有三种情况：
1）关系词直接跟在先行词后面.如：
This is a picture-story book (which) tells you an interedting story.（这是一本给你讲述有趣故事的小人书）
2）先行词后是‘介词 + 关系代词’,如：
This a picture-story book (in which) you can read an interedting story.（这是一本你能够在里面读到有趣故事的小人）
3）先行词后是‘名词 + 介词 + 关系代词’.如：
* This is the picture-story book (the cover of which) is a plastic package.（这是一本封面是塑封的小人书）
* 本题：In geometry,an ellipse may be defined as the locus of all points (the sum of whose distances) from two fixed points is constant.（几何中,椭圆可以定义为两定点的距离之和为一常数的所有点的轨迹）
3、本句中,the sum of whose distances = the sum of the distances of which,它们相互加的关系如下：
1）whose distances (= the distances of which) 中,whose 是修饰 distances 的定语；
2）the sum of whose distances 中,whose distances 整体是修饰 the sum 的定语.
3）the sum of whose distances = the sum of the distances of the points（这些点的距离之和）—— whose 指代 of the points 或 the points