“四群四带”城市化战略格局的“四群”是北部湾城市群和（）、桂北、桂东南城镇群。
A.桂南
B.桂中
C.桂西
参考答案：B
I am as busy as a bee; you bother me with so many questions now?[ ]
A. May
B. Must
C. Can
D. Shall
航空仪表有几种基本环节组成？
