Perhaps you should try some spelling variations:
thong cong » trong cong, tong cong, thong thong
hieu lang » chieu sang, hieu quang, nhieu tang
hoc hieu » hoc thieu, hoc hien, doc hieu
tuong va » truong va, thuong va, luong va
tay dung » xay dung, tac dung, tay nung
tung va » trung va, dung va, vung va
ty dung » ly dung, te dung, ty dong

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

• If you are trying to use Boolean operators, they must be ALL CAPS: hoc hieu lang - thanh ((tung va) OR (tuong va)) thong cong ((ty dung) OR (tay dung)) lam~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc hieu lang - thanh ((tung va) or (tuong va)) thong cong ((ty dung) OR (tay dung)) lam~".
• Adding a wildcard symbol may retrieve word variants: hoc hieu lang - thanh ((tung va) or (tuong va)) thong cong ((ty dung) OR (tay dung)) lam*.