-where-----you----(be)?

-where_____you____(be)?
-I_____(be) to the library
-what do you tink of my answer to the questions
-sorry.what's that?I_______ about something else
A.thought B.had thought C.am thinking D.was thinking
昨天我拜访了他的爷爷
I___ ____ interview ____ his _____ yesterday