Perhaps you should try some spelling variations:
hien xanh » hien hanh, hien nhanh, chieu xanh
hang cong » hang nong, bang cong, thanh cong
dang cong » dung cong
trinh va » trinh van, trinh vat, trinh vi
trinh ve » trinh he, trinh vi, trinh viet
dan toan » van toan, dan than, manh toan
toan cao » toan ban, toan tap

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc hien xanh - hanh ((trinh va) OR (trinh ve)) ((hang cong) or (dang cong)) dan toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hien xanh - hanh ((trinh va) OR (trinh ve)) ((hang cong) OR (dang cong)) dan toan cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc hien xanh - hanh ((trinh va) OR (trinh ve)) ((hang cong) or (dang cong)) dan toan cao".
• Adding a wildcard symbol may retrieve word variants: hoc hien xanh - hanh ((trinh va) OR (trinh ve)) ((hang cong) or (dang cong)) dan toan cao*.