C. is being tested D. has been tested

解析：以上两题答案均为C。考例4中

的now是现在进行时的标志，schoolwor

k与grade(批改)之间存在被动关系，故

选C。从考例5中What’s that noise?可

看出，机器是正被检验中，才会发出噪

音，可见动作是正在进行的，故选C。

（四）、现在完成时和过去完成时的被

动语态：have/has(had)+been+done

6. With the help of high technology, m

ore and more new substances ______

in the past years. [2007 上海卷]

A. discovered B. have discovered

C. had been discovered

D. have been discovered

7. Professor James will give us a

lecture on the Western culture, but