ra lệnh điều tra 
to order an investigation [ ra ] : to go out, exit, give, issue, emit, leave
[ lệnh ] : law, order, command, decree
[ 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
Most Common Compounds Set 1:
Most Common Compounds Set 2 :