I just don’t understand ________ that prevents so many children at school from being as happy as one might expect.
| A．what it is | B．what it does |
| C．what is it | D．why is it |
As the world’s population continues to grow, the ___of food becomes more and more of a concern.
| A．worth | B．supply | C．package | D．list |
I ______ myself more-----it was a perfect day.
| A．shouldn’t have enjoyed | B．needn’t have enjoyed |
| C．wouldn’t have enjoyed | D．couldn’t have enjoyed |
Mary worked here as a ____ secretary and ended up getting a full-time job with the company.
| A．pessimistic | B．temporary | C．previous | D．cautious |
——Hey, can I ask you a favor?
----Sure, _______
| A．Here you are | B．Just as I thought |
| C．How is it going | D．What can I do for you? |
A model or an experiment in a science class can help us see things which wouldremain hidden．
| A．therefore | B．yet | C．otherwise | D．still |