ADJ-GRADED 消息灵通的;(对某一方面的最新消息)敏感的，敏锐的 If you describe someone as switched-on, you mean that they are aware of the latest developments in a particular area or activity. 消息灵通的;(对某一方面的最新消息)敏感的，敏锐的 [informal]
I am very impressed with Brian Hanlon, who seems a switched-on sort of guy.