Mr Liu is ____ unusual teacher. He has written _____ useful book for his students.
—Is the blue ruler _______? —No. _______ ruler is red.
This morning I have _______ art lesson. Art is _______ useful subject.
It is __________ difficult work __________ nobody can do it well.
––Did your mother go to Amy’s party?––No, she __________.
There will be an exhibition of the _____ of dictionary in our city next week. We can learn more about the dictionary’s history there.