单选题 With the higher grade requirements for admission, it has become______more difficult for high school students to be accepted to Madison University.
【正确答案】 B
【答案解析】解析：此处应选择可以修饰空格后面的副词more的词，故副词(B)progressively(日益地)为正确答案。动词或名词(A)、动词(C)和(D)都不能修饰副词。