Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
cao hoi » cau hoi, co hoi, cao hoc
hieu va » hieu qua
cam tuc » cam xuc, cam tu, nam thuc
sac ky » cac ky, sai ky
tuc va » thuc va, truc va, tuc xa
va dan » ca dan, va dao, va dau
ca cau » cua cau, cac cau, can cau

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((sac ky) or (sach y)) nang cao hoi. ((hieu va) OR (lieu va)) cam tuc va dan ca cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sac ky) OR (sach y)) nang cao hoi. ((hieu va) OR (lieu va)) cam tuc va dan ca cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sac ky) or (sach y)) nang cao hoi. ((hieu va) OR (lieu va)) cam tuc va dan ca cau tren".
• Adding a wildcard symbol may retrieve word variants: tu ((sac ky) or (sach y)) nang cao hoi. ((hieu va) OR (lieu va)) cam tuc va dan ca cau tren*.