单选题 Life is DifficultWhat makes life difficult is that the process of facing and solving problems is a painful one. Problems cause    31    , anger, fear or despair. These are    32   feelings, often as painful as any kind of physical pain. And since life   33    an endless series of problems, it is   34    difficult and is full of pain as well as joy.Yet it is in this process of    35    and solving problems that life has its meaning. Problems call forth our 请作答此空    and our wisdom. It is only because of problems that we grow    37     and spiritually. When we want to encourage the    38    of the human spirit, we encourage the human capacity to solve problems, just as in school we deliberately   39     problems for our children to solve. It is through the pain of confronting and resolving that we learn. It is for this reason that    40    people learn not to fear but actually to welcome problems and actually to welcome the pain of problems.