1.She said she didn't take my ruler ,but I am sure she ( ).
A.did
B.is
C.does
D.was
2.He walked slowly ( ) his bad leg.
A.as for
B.at the end of
C.because of
D.in front of
3.The students should ( ) the teacher carefully.
A.listen
B.listen to
C.be listened
D.be listened to