---Does Mike have a knife?
---Yes, he has a very good ________.
---We should do what we can _________ the endangered animals.
---Yes, it’s duty_________ them.
---Could you tell me what ______ at this time yesterday?
---Er, I was reading in my office.
---What's your favorite color?
---________.
---Ken is often heard to apologize to his teacher.
---We often ______ Ken ______ to his teacher.
---Jim is leaving for a holiday.
---Really? Where ________ he ________?
---Do you know _______ the iPhone 4 yesterday?
---Sorry, I have no idea about it.
---A:Whose radio is it?
---B:It's________.
---A:Is this________pocket calculator?
---B:No.It's________.