Question

求助sat语法题！！！

(Unlike) several decades ago, today's librarians teach students to evaluate the accuracy and objectivity of online resources in addition to helping them find particular books.

A原句
B Unlike them of
C Unlike those of
D Contrary to
E Contrary to those
答案是C
请帮忙解释一下其他几个选项为什么不对。 尤其是B选项 。正确答案的those到底指什么？

Answer 1

我一个朋友说的，他去年过的，希望对你有帮助。

Answer 2

第一题我觉得是第一个括号错了，因为主语部分是复数(district's
superintendent
and
budget
director)
第二题我认为是第一个空，因为好像succeed
应该是
succeed
sb
as
sth吧我记得