Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, hang cong
trinh vat » trinh van, trinh luat, sinh vat
trinh va » trinh van, trinh ve, trinh vi
cong dan » cong san, cong tan, huong dan
dan toan » van toan, dan than, manh toan
toan cao » toan ban, toan tap
o chau » 3 chau, moc chau
a chau » ha chau, lai chau, hat chau

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

• If you are trying to use Boolean operators, they must be ALL CAPS: ((o chau) OR (a chau)) tinh - hanh ((trinh va) OR (trinh vat)) nhung cong dan toan cao~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((o chau) or (a chau)) tinh - hanh ((trinh va) OR (trinh vat)) nhung cong dan toan cao~".
• Adding a wildcard symbol may retrieve word variants: ((o chau) or (a chau)) tinh - hanh ((trinh va) OR (trinh vat)) nhung cong dan toan cao*.