central extension of groups

例句：

1. 1. The city is the central hub of the region.
   这个城市是该地区的中心。
2. 2.The central government has been criticized for its handling of the crisis.
   中央政府因处理危机的方式受到批评。
3. 3. The central role of the president in the decision-making process cannot be overstated.
   总统在决策过程中的核心作用不容忽视。