Perhaps you should try some spelling variations:
"de khac thi nghiem de hoc" » "de khac thuc nghiem de hoc", "de khac thi nghiem d hoc", "de khac thi nghiem do hoc", "de khac thi nghiem te hoc", "de khau thi nghiem de hoc", "de khuc thi nghiem de hoc", "de khuat thi nghiem de hoc", "se khac thi nghiem de hoc", "dieu khac thi nghiem de hoc", "de khac thi nghiem du hoc", "de khac thi nghiem dien hoc"
"he khach mai nghiep y hoc" » "he khach lam nghiep y hoc", "he khach xi nghiep y hoc", "he khach cac nghiep y hoc", "he khach trai nghiep y hoc", "he bach mai nghiep y hoc", "he khach san nghiep y hoc", "le khanh mai nghiep y hoc", "he khach mai nghiep ly hoc", "he khach mai nghiep o hoc", "he khach mai nghiep cay hoc"

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("he khach mai nghiep y hoc") or ("de khac thi nghiem de hoc"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("he khach mai nghiep y hoc") OR ("de khac thi nghiem de hoc")).
• Removing quotes may allow a broader search: (( he khach mai nghiep y hoc ) or ( de khac thi nghiem de hoc )).
• Adding a wildcard symbol may retrieve word variants: (("he khach mai nghiep y hoc") or ("de khac thi nghiem de hoc"))*.