Perhaps you should try some spelling variations:
thanh trung » thanh tung
phuong danh » phuong anh, phuong dinh, phuong hanh
phuong dan » phuong doan, huong dan, phuong lan
hieu lang » chieu sang, hieu quang, nhieu tang
hoc hieu » hoc thieu, hoc hien, doc hieu
trung va » truong va, trang va, trung ha
khan cap » than cap, khoan cam, phan cac
khan ap » han ap, khan dam

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 lang - thanh trung va nhung ((phuong dan) or (phuong danh)) ((khan cap) OR (khan ap))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hieu lang - thanh trung va nhung ((phuong dan) OR (phuong danh)) ((khan cap) OR (khan ap)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc hieu lang - thanh trung va nhung ((phuong dan) or (phuong danh)) ((khan cap) OR (khan ap))".
• Adding a wildcard symbol may retrieve word variants: hoc hieu lang - thanh trung va nhung ((phuong dan) or (phuong danh)) ((khan cap) OR (khan ap))*.