____ is a word-formation process by which a word is changed from

____ is a word-formation process by which a word is changed from one word-class into another without the change of form.
A、Blending
B、Affixation
C、Back-formation
D、Conversion
【正确答案】：D
【题目解析】：参考教材P56，转换是一种构词过程，即一个词从一个词类转换为另一个词类而不改变其形式。