in HK, police are call
rude: caai1 lou2, for policewoman : caai1 po4(差婆)
common : caai1 jan4
formal : ging2 caat3
these apply to detectives
more for plain clothes detectives are: zaap6 caai1(雜差), rude: lou5 zaap2(老雜), old saying: ce1 tau2(車頭) or CID(Crime Investigation Department)
aa3 sir (阿sir) can be used to address all law enforcement personnels, and male teachers.