硫代硫酸钠（Na₂S₂O₃）可作为脱氯剂，如Na₂S₂O₃和氯气反应，可将氯气完全转化为Cl^-从而消除氯气对环境的污染，则在该反应中S₂O₃^2-不能转化为（　　）

A．S^2-

B．SO₂

C．S

D．SO₄^2-

Simon is very regretful. If he had been more careful, he _____ such a big mistake.

A．hasn’t made

B．hadn’t made

C．won’t have made

D．wouldn’t have made