Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, hang cong
hiem ngan » kim ngan, viem gan
bang cong » dang cong, bang song, hang cong
doc hiem » doc hieu, hoc hien, doc viet
sinh cua » manh cua, dinh cuu
van toan » van tuan, van tan, van thanh
toan cao » toan ban, toan tap
sinh va » sinh vat, tinh va, dinh van

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc hiem ngan - hanh ((sinh cua) OR (sinh va)) ((nhung cong) or (bang cong)) van toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hiem ngan - hanh ((sinh cua) OR (sinh va)) ((nhung cong) OR (bang cong)) van toan cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc hiem ngan - hanh ((sinh cua) OR (sinh va)) ((nhung cong) or (bang cong)) van toan cao".
• Adding a wildcard symbol may retrieve word variants: doc hiem ngan - hanh ((sinh cua) OR (sinh va)) ((nhung cong) or (bang cong)) van toan cao*.