[填空题]Safety studies have been done on GM salmon.

[填空题]Safety studies have been done on GM salmon.

[填空题]Quite a few (experiment)（）tests have been done, but none of them could help to cure the patient.

[填空题]

What has been done to have fewer cars on the freeways Asking several people to ______.

[填空题]What have Edmond Brothers been
They have been ______.

[单项选择]All （ ） has alreadly been done.
A. can be done
B. should be done
C. that can be done
D. what should be done

[单项选择]What has recently been done to the space
A. The walls have been painted.
B. The walls have been separated.
C. A private office has been built.
D. Bathrooms have been added.

[填空题]

What has been done traditionally better in America ______.

[填空题]Much research bas been done on interviews in general but journalistic interviewing as a specific field has unfortunately ______.

[填空题]Because little research had been done on the explanation of happiness, before going into the lab, Lyubomirsky had done some ______.

[单项选择]Based on research that has been done regarding the relationship between deficits and interest rates it can be concluded that:（）
A. year-to-year data indicate a strong relationship between budget deficits and interest rates but over a more lengthy period, persistently large budget deficits do lead to higher interest rates as implied by the crowding-out model.
B. year-to-year data indicate a loose relationship between budget surpluses and interest rates but over a more lengthy period, persistently large budget deficits do lead to higher interest rates as implied by the crowding-out model.
C. year-to-year data indicate a loose relationship between budget deficits and interest rates but over a more lengthy period, persistently large budget deficits do lead to higher interest rates as implied by the crowding-out model.

[简答题]We have done things we ought not to have done and ____________(应该做的事情却没有做).

[单项选择]A great deal has been done to remedy the situation.
A. maintain
B. improve
C. preserve
D. protect

[单项选择]It is no use （　） what has been done.
A. to regret
B. regretted
C. regretting
D. regret

[简答题]Research has also been done into the way people’s behavior changes in a number of small, seemingly unimportant ways when they lie. (Passage 1)