DQ sec 17-05

Presenters at the seminar, one who is blind, will demonstrate adaptive equipment that allows visually impaired people to use computers.
(A) one who
(B) one of them who
(C) and one of them who
(D) one of whom
(E) one of which

The subject, presenters, must be followed by a limiting appositive such as one of whom, that identifies an individual from among a larger group. Choice D is best: one of whom best serves an appositive to the subject, presenters, because the phrase means “one from among several or many.” Choice A, one who, is unacceptable because one who cannot refer to the plural presenters. Choices B and C are ungrammatical because who competes with one as the subject of is. Choice E employs which, a relative pronoun that does not refer to people (presenters), but only to things.

Q1: 为什么说"who competes with on as the subject of is", who 难道不能修饰one 吗?

Q2: 如果改成"one of them is blind", 是否正确呢?

Q1:

如果是B或者C的话

who修饰的是them

题意是其中的一个人是blind

Q2：

如果是one of them is blind的话，只有两种可能

1.独立的句子，因为前面是逗号－－－－但是没有and连接，使得them显指代对象不明确

2.同位语－－－－但是直接修饰seminar，意思不对

3.插入语－－－显得absurdly

应该是whom做修饰指代