It is __ ___ for a person in his position to make such a mistake.
| A.rare | B.scare | C.usual | D.rarely | 
. 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 |