血液的pH能保持恒定,其中起主要作用的缓冲对是( )
A. HHb-KHb
B. HHbO2-K HbO2
C. NaH2PO4- Na2HPO4
D. H2CO3-NaHCO3
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欲配制与血浆pH相同的缓冲溶液,应选用下列哪一组缓冲对( )
A. HAC-NaAc(pKa=4.75)
B. NaH2PO4-Na2HPO4(pKa=7.20)
C. NH3-NH4Cl(pKa =9.25)
D. H2CO3-NaHCO3(pKa=6.37)
人体血浆中最主要的抗碱成分是( )
A. H2PO4-
B. HCO3-
C. HPO42-
D. H2CO3
0.2 mol/L HAc与0.1mol/L NaOH溶液等体积混合后,溶液中的抗酸成分是( )
A. NaOH
B. Ac-
C. HAc
D. OH-
3. A: Something urgent has come up. Could I postpone our appointment?B：_________________________________________
A. sorry, I’ve got an appointment at 8:30 with Mr. Anderson, the bank manager.
B. Ok. Can we see at 2 clock this afternoon?
C. One moment, please.
D. I look forward to meeting you then.
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