My computer is out of _________ order all of a sudden. Could you do me________ favor and type the plan for me right now?
| A.the; a | B.the; 不填 | C.不填; a | D.不填; 不填 | 
---Della, would you like some potato chips?
  ---No potato chips for me---I’m ______ a diet.
| A.at | B.in | C.on | D.with | 
Harry has been reading all day---he ______ be tired.
| A.should | B.has got to | C.has to | D.must | 
Children have a natural ______ about the world around them. They are interested in everything.
| A.concern | B.purpose | C.curiosity | D.strength | 
---Must I clean the window now?
  ---No, you ______.
| A.mustn’t | B.needn’t | C.can’t | D.may not | 
In order to attract more customers, many supermarkets usually sell their goods at a good ______ at weekends.
| A.discount | B.agreement | C.bargain | D.cost |