简述危机的特点
参考答案：
①不确定性。
②全新性。
工业是国民经济的______，农业是国民经济建设与发展的______产业，交通是经济发展的“______”．
With the teacher's help, he does much ______ in his Chinese study now. [ ]
A. well
B. best
C. better
