Perhaps you should try some spelling variations:
trinh nghien » trinh nghe, kinh nghiem, trinh thiet
tra nghiem » trac nghiem, trai nghiem, thi nghiem
khanh tra » thanh tra, khanh trach, khanh hoa
nghiem du » nghiem dau, nghiem d, nghiem de
trinh he » trinh han, trinh hoa, trinh thi
su khanh » su thanh, vu khanh, su khang
so hoc » co hoc, mo hoc, so hoa
du hoc » tu hoc, duoc hoc

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (( vu bach ((trinh nghien) OR (trinh he)) so hoc ) OR ( su khanh tra nghiem du hoc ))~.
• Adding a wildcard symbol may retrieve word variants: (( vu bach ((trinh nghien) or (trinh he)) so hoc ) or ( su khanh tra nghiem du hoc ))*.