Someone is ringing the doorbell. Go and see .
| A．who it is | B．who is it | C．who is he | D．who he is |
. His sister left home in 1998, and_______since.
| A．had not been heard of | B．had not heard of |
| C．has not been heard of | D．has not heard of |
. The weather in Beijing in winter is colder than_______ in Fuzhou.
| A．one | B．it | C．that | D．what |
Although _____ to stop, he kept on working.
| A．was told | B．telling | C．having told | D．told |
— Why not go and have dinner in a restaurant?
— _______. It’s too expensive.
| A．Why not | B．I agree | C．I’m afraid not | D．I’m sure |
His appearance has changed so much that you _____ not recognize him.
| A．must | B．need | C．may | D．ought |