Perhaps you should try some spelling variations:
thiet hach » thien hach, thuyet hach, thiet hai
nhung cong » dung cong, thong cong, hang cong
hoc thiet » hoc thieu, hoc thuyet, hoc hien
trinh vat » trinh van, trinh luat, sinh vat
trinh va » trinh van, trinh ve, trinh vi
cong van » cong vang, cong san, song van
van toan » van tuan, van tan, van thanh
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 - hanh ((trinh va) OR (trinh vat)) nhung cong van toan cao~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc thiet hach - hanh ((trinh va) OR (trinh vat)) nhung cong van toan cao".
• Adding a wildcard symbol may retrieve word variants: hoc thiet hach - hanh ((trinh va) OR (trinh vat)) nhung cong van toan cao*.