普通混凝土、高强度混凝土、高性能混凝土分别可用（）表示。

A.HPC.OPC.HSC

B.OPC.HSC.HPC

C.HSC.HPC.OPC

D.HPC.HSC.OPC

I feel it's an honor（）to attend the opening ceremony of the new bank.

A.to invite

B.of being invited 

C.to be invited

D.having invited