能在溶液中大量共存的一组离子是 [ ]

A．NH₄⁺、Ag⁺、PO₄^3-、Cl^-

B．Fe³⁺、H⁺、I^-、HCO₃-

C．K⁺、Na⁺、NO₃^-、MnO₄^-

D．Al³⁺、Mg²⁺、SO₄^2-、CO₃^2-

— When _________ this kind of computer ________?

— Last year. [ ]

A. did; use  

B. was; used  

C. is; used  

D. are; used