Complete the following statements with proper words or expressions according to the course book.According to the positions which affixes occupy in words, affixation falls into two subclasses: ( ) and suffixation.
【正确答案】：PREFIXATION
【题目解析】：According to the positions which affixes occupy in words, affixation falls into two subclasses: prefixation and suffixation. 根据词缀在词中出现的位置，词缀法可分为两类：前缀法和后缀法。
