Those who steal books in the library _____ not be allowed to borrow any again in the future.
| A.shall | B.must | C.may | D.can | 
--The plane is due to take off at 7∶50 from the airport.
  --________ we fail to arrive there in time?
| A.What if | B.As if | C.Even if | D.Only if | 
--They ________ out the problem, but failed.
  --What a shame ! I never thought it was going to happen like that.
| A.managed to work | B.managed working | 
| C.sought working | D.sought to work | 
--Let’s go there by taxi.
  --It’s not far from here, I prefer ________.
| A.walking to take a taxi | B.to walk rather than take a taxi | 
| C.walk to taking the taxi | D.to walk rather than to take a taxi | 
They ________ the train until it disappeared in the distance.
| A.saw | B.watched | C.noticed | D.observed | 
As we all know, children are always ________ about everything fresh to them.
| A.strange | B.amusing | C.curious | D.conscious |