21. The film Harry Potter was quite      hit across the world, bringing in      income of box office over millions of dollars within five months.

A. /; an                          B. a; /                   C. a; an                 D. a; the

22. As I grew up in a small town at the foot of a mountain, the visit to the village _______ scenes of my childhood.

A. called up               B. called for      C. called on      D. called in

23. The cost of living in Glasgow is among the lowest in Britain, ________ the quality of life is probably one of the highest.

A. since                    B. when         C. as               D. while