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1·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。

2·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。