老题求解

alexcui31707

GWD-29-Q29                                                                                                                                                               Most of Portugal’s 250,000 university students boycotted classes in a one-day strike to protest a law that requires them to contribute $330 a year toward the cost of higher education, previously paying $7 per year. A.        year toward the cost of higher education, previously paying $7 per year B.        year toward the cost of higher education, for which was previously paid $7 per year C.        year, compared to the previously $7 per year, toward the cost of higher education D.        year toward the cost of higher education, instead of the $7 per year required previously E.        year as opposed to the $7 per year required previously for the cost of higher education 这个题目对于这个B选项，我比较认为是这个which是指代the cost of higher education，那么这个这个句子就是 year toward the cost of higher education,  which was previously paid  for $7 per year.我感觉多余的是for 但实际上还好，但不明白从句子上怎么少主语了。不明白，请大侠给解释

daisyjin

which was previously paid 7 per year for the higher education.
我是这样理解的，不知对否