Perhaps you should try some spelling variations:
trach nhiem » trac nghiem
trai nghiem » trac nghiem, thi nghiem
cong trach » thong trach, cong tac, cong trinh
nghiem de » nghiem d, nghiem do, nghiem te
nhiem tu » nhiem thuc, nhiem huu, nghiem su
toc sach » hoc sach, doc sach, thuoc sach
su sach » so sach, vu sach
tu hoc » te hoc
de hoc » te hoc, du hoc, dien hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( thu cong trach nhiem tu hoc ) or ( ((su sach) or (toc sach)) trai nghiem de hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( thu cong trach nhiem tu hoc ) OR ( ((su sach) OR (toc sach)) trai nghiem de hoc )).
• Adding a wildcard symbol may retrieve word variants: (( thu cong trach nhiem tu hoc ) or ( ((su sach) or (toc sach)) trai nghiem de hoc ))*.