Besides the electrons, an atom also contains positive electrical particles______total charge must be equal to that of the electrons.

A．which

B．that

C．whose

D．of which

血浆缓冲系统中，缓冲能力最强的是（）

A.KHb/Hb

B.血浆蛋白-Na/血浆蛋白

C.NaHCO₃/H₂CO₃

D.Na₂HPO₄/NaH₂PO₄

E.KHCO₃/H₂CO₃