21. It is ___ honor for anyone to be elected ____ manager of such an important department.
   A. / ; a             B. / ; /             C. a ; a           D. an ; / 
22. --- I bet someone stole my backpack.
   --- Well, you _____ have kept an eye on it.
   A. may             B. can             C. would        D. should
23. The first time Johnson went to Spain, he managed to make himself ____ with his ____ Spanish.
A. understand; broken                   B. understood; break   
C. understood; broken                  D. understand; break