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在一只杯中倒满水,并在杯上放一张纸板。然后用手将纸板紧贴在杯子口,倒放在一个洗涤池或浴盆上。现在移开你的手。嗒——嗒嗒嗒!水不会
Fill a cup with water and place a cardboard on the cup. Then place the cardboard in the mouth of the cup by hand and place it on a sink or bath. Now remove your hand. Hey - hey! The water won’t