下列离子方程式的表达正确的是（　　）

A．CuSO₄溶液与Ba（OH）₂溶液混合：Ba²⁺+SO₄^2-=BaSO₄↓

B．NaHCO₃溶液与稀硫酸混合：HCO₃^-+H⁺=H₂O+CO₂↑

C．NaHSO₃溶液与NaHSO₄溶液混合：HSO₃^-+HSO₄^-=SO₄^2-+H₂O+SO₂↑

D．Ca（OH）₂溶液中通入过量CO₂：Ca²⁺+2OH^-+CO₂=CaCO₃↓+H₂O

Process so far has been very good．______，we are sure that the project will be completed on time．

A．However

B．Otherwise

C．Therefore

D．Besides