如图所示为“铁链环”结构，图中两环相交部分A、B、C、D 表示物质间的反应。下列对应部分反应的离子方程式书写不正确的是
A．Cl2＋2OH－=Cl－＋ClO－＋H2O
B．Cu2＋＋2OH－=Cu(OH)2↓
C．Cu2＋＋SO42-＋Ba2＋＋2OH－=BaSO4↓＋Cu(OH)2↓
D．OH－＋HCO3-=H2O＋CO32-
The children all turned ____ the famous actress as she entered the classroom. 
| A．looked at | B．to look at |
C．to looking at | D．look at |
Edward, you play so well. But I ______ you played the piano. 
| A．didn’t know | B．hadn’t known |
C．don’t know | D．haven’t known |
She brought with her three friends, none of ______ I had ever met before. 
| A．them | B．who | C．whom | D．these |
I tried phoning her office, but I couldn’t _______. 
| A．get along | B．get on | C．get to | D．get through |
His sister left home in 1998, and _______since. 
| A．had not been heard of | B．has not been heard of |
C．had not heard of | D．has not heard of |