The primary function of suffixes is to（）.
A、change the word-class of roots
B、change the meaning of stems
C、change the grammatical function of stems
D、change the structure of roots
【正确答案】：C
【题目解析】：The primary function of suffixes is to change the grammatical function of stems. 后缀的主要功用是改变词干意义的语法功能。
