31. All books ______ to the library more
题型:选择题
问题:
31. All books ______ to the library more than three days late will be subject to a fine.
A.return
B.returning
C.to return
D.Returned
31. All books ______ to the library more than three days late will be subject to a fine.
A.return
B.returning
C.to return
D.Returned