—I’m sure Andrew will win the first prize in the final.

—I think so. He ________ for it for months.

A．is preparing

B．was preparing

C．had been prepared

D．has been preparing

25℃时，K_w =1.0×10^－14；100℃时，K_w =5.4×10^－13。对有关溶液pH说法正确的是

A．100℃时，pH=12的NaOH(aq)和pH=2的H₂SO₄(aq)恰好中和，所得溶液的pH=7

B．100℃时，0.2 mol/L Ba(OH)₂(aq)和0.2 mol/L HCl(aq)等体积混合，所得溶液的pH=7

C．25℃时，0.2 mol/L NaOH(aq)与0.2 mol/L CH₃COOH(aq)恰好中和，所得溶液的pH="7"

D．25℃时，pH=12的氨水和pH=2的H₂SO₄(aq)等体积混合，所得溶液的pH＞7