47、It could be inferred from the last paragraph that ___________.

A. culture exercises an influence over social interrelationship

B. courteous convention and individual interest are interrelated

C. various virtues manifest themselves exclusively among friends

D. social interrelationships equal the complex set of cultural conventions

（本题分值：1.5分）【正确答案】A

48、Families in frontier settlements used to entertain strangers ___________.

A. to improve their hard life

B. in view of their long-distance travel

C. to add some flavor to their own daily life

D. out of a charitable impulse

（本题分值：1.5分）【正确答案】C

49、The tradition of hospitality to strangers ___________.

A. tends to be superficial and artificial

B. is generally well kept up in the united States

C. is always understood properly

D. has something to do with the busy tourist trails

（本题分值：1.5分）【正确答案】B

50、What's the author's attitudes toward the American's friendliness?

A. Favorable.

B. Unfavorable.

C. Indifferent.

D. Neutral.

（本题分值：1.5分）【正确答案】A