điều tra kỹ 
to investigate carefully [ điều ] : (1) thing, matter, item; article (of penal code, constitution); (2) smoking pipe; (3) bird [=chim]
[ tra ] : (1) to consult, look up; (2) to fit in; (3) to add; (4) to apply
[ kỹ ] : (1) carefully; careful, thorough; (2) prostitute; (3) skillful
Most Common Compounds Set 1:
Most Common Compounds Set 2 :