单选题 .  More than forty thousand readers told us that they looked for in close friendships, what they expected     1    friends, what they were willing to give in     2    , and how satisfied they were     3    the quality of their friendships. The     4    give little comfort to social critics.
    Friendship     5    to be a unique form of     6    bonding. Unlike marriage or the ties that     7    parents and children, it is not defined or regulated by     8    . Unlike other social roles that we are expected to     9    —as citizens, employees, members of professional societies and     10    organizations—it has its own principle, which is to promote     11    of warmth, trust, love, and affection     12    two people.
    The survey on friendship appeared in the March     13    of Psychology Today. The findings     14    that issues of trust and betrayal(背叛)are     15    to friendship. They also suggest that our readers do not     16    for friends only among those who are     17    like them, but find many     18    differ in race, religion, and ethnic(种族的) background. Arguably the most important     19    that emerges from the data,     20    , is not something that we found—but what we did not.1.