______ with high demand and serious shortage of preschools, the local government is undertaking a major expansion.

A．Faced

B．Being faced

C．Facing

D．Having faced

下列离子方程式中正确的有（　　）

A．稀硫酸滴加在铜片上：Cu+2H⁺=Cu²⁺+H₂↑

B．氧化铁粉末溶于稀盐酸：Fe₂O₃+6H⁺=2Fe³⁺+3H₂O

C．氧化镁与硝酸（aq）反应：O^2-+2H⁺=H₂O

D．硫酸镁（aq）与氢氧化钡（aq）混合：Ba²⁺+SO₄^2-=BaSO₄↓