key sectors的用法和樣例：
例句
- He revealed that half the officers in a key unit failed a polygraph test last year.
據他透露，半數某關鍵部門的警官都沒能通過去年的測謊鑒定。 - Since its inception, PDC has expanded at a rapid pace and is now a key department for delivery of banking systems within the HSBC Group.
自成立以來，軟體開發中心高速發展，現已成為滙豐集團銀行系統的關鍵部門。
