Perhaps you should try some spelling variations:
trai nghiep » trai nghiem, trac nghiem, mai nghiep
trach nhiem » trac nghiem
sach trach » sach tranh, sach truc, sat trach
vu khach » vu khanh, vu khac, vay khach
tu sach » thu sach, su sach, te sach
nhiem d » nghiem d, nghiem de, nghiem do
tu hach » tu hanh, tu cach, tac hach
vu hoc » va hoc, du hoc, vi hoc
tu hoc » te hoc
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: (( tu sach trach nhiem d hoc ) or ( ((vu khach) or (tu hach)) trai nghiep ((vu hoc) or (tu hoc)) ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu sach trach nhiem d hoc ) OR ( ((vu khach) OR (tu hach)) trai nghiep ((vu hoc) OR (tu hoc)) )).
• Adding a wildcard symbol may retrieve word variants: (( tu sach trach nhiem d hoc ) or ( ((vu khach) or (tu hach)) trai nghiep ((vu hoc) or (tu hoc)) ))*.