A s____ can be a bound root, a free morpheme, or a derived form itself to which a derivational affix can be added.
出自:信阳师范大学英语语言学

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