A.They are relatively uniform in color and design

B.They appear more formal than other passports

C.They are a shade of red bordering on brown

D.They vary in color from country to country

A.They must endure wear and tear

B.They must be of the same size

C.They must be made from a rare material

D.They must follow some common standards

A.They look more traditional

B.They look more official

C.They are favored by airlines

D.They are easily identifiable

A.For beauty

B.For variety

C.For visibility

D.For security