【正确答案】：
PREFIXATION DOES NOT GENERALLY CHANGE THE WORD CLASS OF THE STEM; IT ONLY MODIFIES ITS MEANING. E.G. TREAT-MALTREAT.
SUFFIXATION, ON THE OTHER HAND, CHANGES THE WORD CLASS INSTEAD OF ITS MEANING. E.G. EMPLOY-EMPLOYER.
【题目解析】：前缀法一般不会改变词干的词类，它只会修改它的意思。例如对待-虐待。另一方面，后缀改变了词类而不是它的意思。例如，雇用-雇主。