The idea for the new machine came to Mr．Baker ________ to his invention recently．
A.while devoting
B.while devoted
C.while he was devoted
D.while devoting himself．
网友回答
C解析while后主语及助动词不能省略，因为两句主语不一致。如主语一致，则：Mr Baker thought of the idea for the new machine (B / D) to his invention recently.