21. Welcome to our online mall! If you buy ______iphone4 here, you can get a watch for _____free.
A. a; / B. an; the C. an; / D. the; the
22. ----How beautiful the university is, Professor Wu.
----So it is. I ______ here for four years and my daughter is studying here too.
A. studied B. have studied C. was studied D. had studied
