Perhaps you should try some spelling variations:
lang khoa » hang khoa, dang khoa, long khoa
hieu quan » lieu quan, thien quan, lien quan
khoa hoi » khoan hoi, khoa hoc, khoa doi
ky lang » ky nang, ky dang, ky tang
thai do » thay doi, thai den
va hanh » van hanh, va thanh, va danh
cuu tre » cau tren, cau treo
cua tre » cua te, cua triet, dua tren
do va » do van, so va

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu cac ky lang khoa hoi. ((hieu quan) or (hieu qua)) thai do va hanh vi ((cuu tre) OR (cua tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu cac ky lang khoa hoi. ((hieu quan) OR (hieu qua)) thai do va hanh vi ((cuu tre) OR (cua tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu cac ky lang khoa hoi. ((hieu quan) or (hieu qua)) thai do va hanh vi ((cuu tre) OR (cua tre))".
• Adding a wildcard symbol may retrieve word variants: tu cac ky lang khoa hoi. ((hieu quan) or (hieu qua)) thai do va hanh vi ((cuu tre) OR (cua tre))*.