A.distinct
B.distinctive
C.distinguished
D.distinguishing

A.square
B.oval
C.circular
D.oblong
A.peaceful
B.quiet
C.silent
D.personal
A.people are unconcerned about politeness nowadays.
B."thank you" remains the best expression of gratitude.
C.there is a variety of expressions of appreciation.
D.there are more formal expressions than informal ones.