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 d » nghiem de, nghiem do, nghiem _
tu sach » thu sach, su sach, tu cach
te sach » toc sach
d hoc » du hoc, ad hoc, de 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 (te hoc)) ) or ( ((tu sach) or (te sach)) trai nghiem d hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( thu cong trach nhiem ((tu hoc) OR (te hoc)) ) OR ( ((tu sach) OR (te sach)) trai nghiem d hoc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( thu cong trach nhiem ((tu hoc) OR (te hoc)) ) or ( ((tu sach) or (te sach)) trai nghiem d hoc ))".
• Adding a wildcard symbol may retrieve word variants: (( thu cong trach nhiem ((tu hoc) OR (te hoc)) ) or ( ((tu sach) or (te sach)) trai nghiem d hoc ))*.