阅读下面短文，掌握其大意，然后从第31至第40小题所给的A、B、C、D四个选项中，选出最佳选项，并在答题卡上将该项涂黑。
A high school history teacher once told us, “If you make one close friend in school, you will be most fortunate. A true friend is someone who stays with you for life."   31  _ teaches that he was right. Good friendship is just not easily formed.
It is possible that we simply do not stay in one place long enough for true friendship to  32  . However, there can be no disagreement on the need for each of us to think carefully about the kind of friendship we want.
To most of us, friendships are considered very important, but we need to have clear in our minds the kinds of friendship we want. Are they to be close or   33   at arm's length? Do we want to   34     ourselves or do we want to walk on the surface? For some people, many friendships on the surface are quite enough—and that's all right. But at some point we need to make sure that our expectations are the same as our friends' expectations. The sharing of _  35   experience including our tears as well as our dark dreams is the surest way to deepen friendships. But it must be undertaken(进行) slowly and carried on only if there are sign of interest and action in return.
What are some of the _  36  _ of friendship? The greatest is the attraction to expect too much too soon. Deep relationships _  37  _ time. Another “major difficulty" is the selfishness to think one “possesses" the other, including his time and attention. Similarly, friendships     38  actions in return. In other words, you must give as much as you take. Finally there is a question of taking care of. Unless you spend _  39  _ time together, talking on the phone, writing letters, doing things together, friendships will die    40   .
31. A. Knowledge       B. Teachers                C. Experience               D. Parents
32. A. design           B. intend           C. develop          D. appear
33. A. remained         B. left             C. kept                       D. stayed
34. A. own             B. owe           C. share                D. spare 
35. A. social            B. ordinary               C. good                        D. personal
36. A. difficulties        B. differences                  C. advantages                D. things
37. A. cost                     B. spend                          C. ask               D. take 
38. A. require           B. request                    C. depend                     D. suggest
39. A. reasonable        B. comfortable                 C. less                          D. a lot
40. A. for                             B. away                           C. out                          D. from