A. which I think is
B. which I think it is
C. I think which is
D. of which I think it is
A. That's OK
B. You are right
C. It's up to you
D. It's a secret
A. was ; was
B. was ; were
C. were ; were
D. were ; was
A. Chinese old stone
B. old stone Chinese
C. Chinese stone old
D. old Chinese stone