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| element of group Any of the divalent electropositive metals beryllium, magnesium, calcium, strontium, barium, and radium, belonging to group 2A of the periodic table; alkaline earth metals (任何带正二价电荷的金属，如：铍、镁、钙、锶、钡、镭属于周期表的第2A族。) | |||
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