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#1
01-26-2018, 06:02 PM
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The real reason why escalator stairs have grooves
 If youâ??re one of the millions of Americans who use escalators each year, you are probably deeply familiar with the vertical grooves that cover each stair. أكثر... ??????? ??????: The real reason why escalator stairs have grooves || ??????: ahlam1399 || ??????: اسم منتداك
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