Perhaps you should try some spelling variations:
trai nghiem » trac nghiem, thi nghiem
trach nhiem » trac nghiem
cong trach » thong trach, cong tac, cong trinh
nhiem thu » nhiem thuc, nghiem thuc, nghiem thi
sach trai » sach tai, sach tranh, khach trai
thu hoc » tu hoc, thu hoi, tru hoc
tu sach » thu sach, su sach, te sach
de hoc » te hoc, du hoc, dien hoc
d hoc » du hoc, ad hoc, y 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 thu hoc ) or ( tu sach trai nghiem ((d hoc) or (de hoc)) ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( thu cong trach nhiem thu hoc ) OR ( tu sach trai nghiem ((d hoc) OR (de hoc)) )).
• Adding a wildcard symbol may retrieve word variants: (( thu cong trach nhiem thu hoc ) or ( tu sach trai nghiem ((d hoc) or (de hoc)) ))*.