Some magnets may have a mark to identify which surface is the northpole.
有些磁铁可能有标志以确定哪些表面是北极。
Some magnets may have a mark to identify which surface is the northpole .
有些磁铁可能有标志（红色斑点或其他一些标志），以确定哪些表面是北极。
Some magnets may have a mark to identify which surface is the northpole .
有些磁铁可能有标志（红色斑点或其他一些标志），以确定哪些表面是北极。
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