当pH = 5.00时,0.20 mol/L二元弱酸(H2A)溶液中,H2A的浓度为 ( )(设H2A的pKa1 = 5.00,pKa2 = 8.00)
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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