一般来说指代是就近指代，即离代词最近的单复数相同的名词。

可是0g103怎么是好像优先指代主语啊？？？望nn指点

103. Students in the metropolitan school district lack math skills to such a large degree as to make it difficult to absorb them into a city economy becoming ever more dependent on information-based industries.

(A) lack math skills to such a large degree as to make it difficult to absorb them into a city economy becoming

(B) lack math skills to a large enough degree that they will be difficult to absorb into a city’s economy that becomes

(C) lack of math skills is so large as to be difficult to absorb them into a city’s economy that becomes

(D) are lacking so much in math skills as to be difficult to absorb into a city’s economy becoming（E）

(E) are so lacking in math skills that it will be difficult to absorb them into a city economy becoming