______ are those that cannot occur as separate words without adding other morphemes( )

A. Free roots
B. Free morphemes
C.Bound morphemes
D. Meaningful units
出自:信阳师范学院-英语词汇学

完成拼图验证

按住下方滑块,将拼图拖到缺口处后松开。

拼图背景,将小拼图拖到缺口处
向右拖动滑块