下列离子方程式正确的是（　　）

A．往碳酸氢钙溶液中滴入少量氢氧化钠溶液：OH^-+HCO₃^-+Ca²⁺=CaCO₃↓+H₂O

B．将一小块金属钠投入到硫酸铜溶液中：2Na+Cu²⁺═Cu+2Na⁺

C．NaHCO₃溶液显碱性：HCO₃^-+H₂O

OH^-+H₂CO₃

D．氯气溶解于水：Cl₂+H₂O

12H⁺+Cl^-+ClO^-

I'm not a little tired today after giving the room a thorough cleaning and I have never had

______ today.  [ ]

A. as tiring a day as  

B. as a tiring day  

C. tiring as a day as  

D. day as a tiring as