Perhaps you should try some spelling variations:
nghien dan » nghiep dan, nghe dan, nguyen dan
khanh trac » khanh trach, khanh tra, thanh tra
nghiem dau » nghiep dau, nghiem va, nghiem ban
nghia dan » nghe dan, nghia mac, nghia xa
xac thai » rac thai, sac thai, xa thai
vu khanh » vu thanh, van khanh, duy khanh
dau hoc » dai hoc, du hoc, dan hoc
su xac » pu xac, su cac

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( su xac thai ((nghien dan) or (nghia dan)) hoc ) or ( vu khanh trac nghiem dau hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( su xac thai ((nghien dan) OR (nghia dan)) hoc ) OR ( vu khanh trac nghiem dau hoc )).
• Adding a wildcard symbol may retrieve word variants: (( su xac thai ((nghien dan) or (nghia dan)) hoc ) or ( vu khanh trac nghiem dau hoc ))*.