--Excuse me, I don't think you can smoke here.
---Really sorry. I ______ this is a non-smoking room.
| A．didn't know | B．don't know | C．have no idea | D．haven't known |
The problem is so complex that I'm afraid it will take me several hours to________．
| A．put out | B．set out |
| C．break out | D．figure out |
George once told me that he would visit our house，but，for various reasons，he________so far.
| A．didn't | B．hasn't |
| C．hadn't | D．wouldn't |
The newlylearnt words will be impressed on us only if they are ________used in everyday communication.
| A．gradually | B．accurately |
| C．familiarly | D．frequently |
A New York couple have been killed in a car crash on their way to hospital，but the unborn baby________the accident.
| A．experienced | B．survived |
| C．escaped | D．fled |
________that the government can clear up official corruption，we are________about the future of our country.
| A．Convinced；optimistic | B．Convincing；optimistic |
| C．Convinced；pessimistic | D．Convincing；pessimistic |