Which of the following can summarize the feature of American's friendship

A．They expect standing friendship.
B．They'd like to establish good relationship between their two families,
C．They expect their friends' help in time of difficulty.
D．They hope to receive hospitality from their friends although they couldn't return.

A．Americans are ready to share their home life with foreigners.
B．Though Americans are very friendly and hospitable, they are reluctant to spend too much time with visitors.
C．Friendships between Americans are close but short.
D．Americans would like to include foreigners in their private lives.