Perhaps you should try some spelling variations:
hang cau » hang dau, hang ca, nhung cau
cach tu » cach thuc
sach tu » sach thu, sach ty, sach uu
cam duc » cam xuc, cao duc, pham duc
dan cua » dan ca, ban cua, dai cua
hieu va » lieu va, hieu qua
va cam » va cham, va cac, va cao
va dan » ca dan, va dao, va dau
da cua » dai cua, day cua, dam cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc ((sach tu) or (cach tu)) hang cau hoi. hieu va cam duc va dan ((da cua) OR (dan cua)) viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc ((sach tu) OR (cach tu)) hang cau hoi. hieu va cam duc va dan ((da cua) OR (dan cua)) viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc ((sach tu) or (cach tu)) hang cau hoi. hieu va cam duc va dan ((da cua) OR (dan cua)) viet".
• Adding a wildcard symbol may retrieve word variants: toc ((sach tu) or (cach tu)) hang cau hoi. hieu va cam duc va dan ((da cua) OR (dan cua)) viet*.