下列离子方程式，书写正确的是（　　）

A．盐酸与石灰石反应CO₃^2-+2H⁺=CO₂↑+H₂O

B．硫酸铜溶液中滴加氢氧化钡溶液Ba²⁺+2OH^-+Cu²⁺+SO₄^2-=BaSO₄↓+Cu（OH）₂↓

C．硝酸银溶液中加入铜粉Ag⁺+Cu=Cu²⁺+Ag

D．铁与稀盐酸反应2Fe+6H⁺=2Fe³⁺+3H₂↑

Africa is actually connected with Asia at the spot ___ the Suez Canel was dug.

A．when

B．where

C．which

D．and