Perhaps you should try some spelling variations:
tham nghiem » trac nghiem, thuc nghiem, thu nghiem
trai nghiem » trac nghiem
khach trai » khac trai, khanh tra, kham trai
thi nghiem » thuc nghiem
nghiem _u » nghiem _, nghiem su, nghiem xu
so sanh » do sanh
_u hoc » tu hoc, du hoc, su hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( vay khach trai nghiem _u hoc ) or ( so sanh ((tham nghiem) OR (thi nghiem)) _ hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( vay khach trai nghiem _u hoc ) OR ( so sanh ((tham nghiem) OR (thi nghiem)) _ hoc ))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( vay khach trai nghiem _u hoc ) or ( so sanh ((tham nghiem) OR (thi nghiem)) _ hoc ))*".