“This is ________ most useful reference book,”a teacher from ________ European country told us in class．

1. A.
   the; a
2. B.
   a；不填
3. C.
   不填；不填
4. D.
   a; a

 “This is ______ most useful reference book,” a teacher from ______ European country told us in class.

       A. the; a                       B. a; 不填                    C. 不填; 不填             D. a; a

“This is ______ most useful reference book,” a teacher from ______ European country told us in class.

       A. the; a                       B. a; 不填                    C. 不填; 不填             D. a; a

 “This is ______ most useful reference book,” a teacher from ______ European country told us in class.

    A. the; a               B. a; 不填          C. 不填; 不填       D. a; a