Pivot tube,inner tube,是什么钢管?

Pivot tube,inner tube,是什么钢管? inner tube 是什么? pivot pivot butyl inner tube 主要用于什么车子上? tube,use,huge,cute,us,sun,mum,duck,tub,mule,cup,bus,的U分别是长音还是短音?十万火急! tube tube Tube inner inner inner tube,use,huge,cute,us,sun,mum,duke,tub,mule,cup,bus中的U分别是长音还是短音?十万火急!对不起 The family would then sit in a circle around the inner tube and spend the evening chewing on it.(翻 PIVOT BUSHING什么意思 Excel 里面Pivot 英语pivot point inner peace inner 、 inner peace