11. --- Could I use your camera?
--- Sure, ____.
A. pardon me B. go ahead C. good idea D. forget it
12. It was three years ago ___ we came to study here.
A. that B. how C. which D. when
13. Xi’an is _____ big city, ______ city that is famous for its long history.
A. a, a B. a; the C. the; a D. the; the
