Perhaps you should try some spelling variations:
thanh trung » thanh tung
thiet hach » thien hach, thuyet hach, thiet hai
hoc thiet » hoc thieu, hoc thuyet, hoc hien
dai duong » dai cuong, hai duong, dai luong
dan dung » van dung, tin dung, ap dung
cong tan » cong tac, cong san, cong thanh
tan phan » toan phan, than phan, van phan
phan dau » phan tu, hang dau

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 ((dan dung) or (dai duong)) cong tan phan dau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc thiet hach - thanh trung ((dan dung) OR (dai duong)) cong tan phan dau.
• Adding a wildcard symbol may retrieve word variants: hoc thiet hach - thanh trung ((dan dung) or (dai duong)) cong tan phan dau*.