----Have you seen____pen﹖I left it here this morning. -----Is it____black one﹖I think I saw it somewhere.
. He misunderstood _____ I said.
. The trouble is _____ we are short of hands.
The guide showed the travelers _____ of the factory.
We should mind our behaviour ______ public.
Excuse me, I have no ______ on me. Can you _____ the note of 100 yuan ?