Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, hang cong
hieu cach » hieu cac, chieu sach, hieu ca
trinh van » trinh han, trinh quan, trinh toan
dang cong » dung cong
hoc hieu » hoc thieu, hoc hien, doc hieu
dan toan » van toan, dan than, manh toan
toan cao » toan ban, toan tap
tinh va » tich va, trinh vat, tinh gia

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc hieu cach - nhanh ((tinh va) or (trinh van)) ((nhung cong) or (dang cong)) dan toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hieu cach - nhanh ((tinh va) OR (trinh van)) ((nhung cong) OR (dang cong)) dan toan cao.
• Adding a wildcard symbol may retrieve word variants: hoc hieu cach - nhanh ((tinh va) or (trinh van)) ((nhung cong) or (dang cong)) dan toan cao*.