请教大全sec18－17

17.   The pattern of
whisker spot on the face of a male lion, like human fingerprints, are a
lifelong means of identification, since they are both unique and unchanging.

(A) like human fingerprints, are a
lifelong means of identification, since they are both unique and unchanging

(B) like human fingerprints, is a
lifelong means of identification, since it is both unique and unchanging

(C) like human fingerprints, is a
means of identification for life, being both unique and unchanging

(D) since they are both unique and
unchanging, are, like human fingerprints, are a means of identification for
life    （B）

(E) both unique and unchanging,
are, like human fingerprints, a lifelong means of identification

答案是 B，我的问题是B中的it会不会存在指代不清的问题？另外being的主语是the pattern，而且being可以表示原因，C为什么不行？

我觉得B中的it不会出现指代问题,like human fingerprints作为插入语，从句主语优先指代主语主语since从句主语指代the pattern应该不会有问题

而Ｃ选项根据ＥＴＳ的逻辑，being主语可能有歧义，语法上修饰life逻辑上修饰pattern

恩，在A of B的结构中由于一般主词是Ａ所以代词也一般指代Ａ，但也有例外情况

但这里也在强调从句的代词指代，一般从句中出现的代词优先指代主句中的主语，特别是定语从句中出现的代词更是优先指代先行词．

楼上说的分词修饰谁的问题，感觉ＯＧ中好像有逗号后分词被它解释成有歧义的，也可能是我记错了

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