Perhaps you should try some spelling variations:
thiet hach » thien hach, thuyet hach, thiet hai
truong cao » truong dai
hoc thiet » hoc thieu, hoc thuyet, hoc hien
trung cua » truong cua, trung tuan, trung cap
cong van » cong vang, song van, cong tan
cong san » cong tac
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 thiet hach - thanh ((trung cua) or (truong cao)) nhung ((cong van) OR (cong san)) toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc thiet hach - thanh ((trung cua) OR (truong cao)) nhung ((cong van) OR (cong san)) toan cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc thiet hach - thanh ((trung cua) or (truong cao)) nhung ((cong van) OR (cong san)) toan cao".
• Adding a wildcard symbol may retrieve word variants: hoc thiet hach - thanh ((trung cua) or (truong cao)) nhung ((cong van) OR (cong san)) toan cao*.