The maipractical advantage of lower pairs is their better ability to trap lubricant betweetheir ______ surfaces.
· enveloping
· mating
· outer
· outside
出自:佳木斯大学语言治疗学

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