1. Letterboxes are much more _______ in the UK than in the US, where most people have a mailbox instead. 

   A. common       B. normal               C. ordinary             D. usual   

2. The practice of hanging clothes across the street is a common ______in many parts of the city.

   A. look          B. sign                 C. sight                    D. appearance

3. When ______ different cultures, we often pay attention only to the differences without noticing the many similarities.

   A. compared      B. being compared       C. having comparing             D. comparing