—Where are the papers for the Smith project?
—They are in the folder “S”．
A. marking
B. marked
C. to be marked
D. to mark
网友回答
A. marking
(答案→)B. marked
C. to be marked
D. to mark
解析：答案：B 考查非谓语动词。句意为：——史密斯工程需要用到的那些文件放到哪里了？——它们被放在标有“S”标记的文件夹里。folder和mark之间是动宾关系，所以要用过去分词形式marked。故答案选B。