对被监管部门批准的保险公司筹备期描述正确的是（）
A.时间为一年
B.时间为六个月
C.期间可以开展业务
D.期间不可以开展业务
参考答案：A, D
Which of the following types of unemployment is most likely caused by long-run changes that eliminate some jobs while generating others for which unemployed workers are not qualified（）
A. Frictional.
B. Structural.
C. Cyclical.
简述GPS卫星的导航电文。
