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这里有四张扑克牌全部扣在桌上,一次必须翻过来其中的三张,最少要几次才能把四张牌全部翻转过来呢?你来试试吧。
Here are four cards buckle all on the table, one must turn over three of them, at least a few times to flip all four cards over it? You try.