Perhaps you should try some spelling variations:
hieu suat » hieu luat, hieu qua
hanh thai » nhanh thai, hinh thai, hanh tai
thai cua » than cua, tai cuc, tri cua
sang lai » sang tai, sang lap, mang lai
hieu sau » hieu su, tieu su, hieu va
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
lai hoi » dai hoi, lai hoa, lai roi
ky sang » ky nang, ky dang, ky tang
xuc va » tuc va, luc va, xac va
cua tu » cua tuc, cua su, cua cu

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky sang lai hoi. ((hieu sau) OR (hieu suat)) chat ((xuc va) or (duc va)) hanh thai cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky sang lai hoi. ((hieu sau) OR (hieu suat)) chat ((xuc va) OR (duc va)) hanh thai cua tu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky sang lai hoi. ((hieu sau) OR (hieu suat)) chat ((xuc va) or (duc va)) hanh thai cua tu".
• Adding a wildcard symbol may retrieve word variants: tu sach ky sang lai hoi. ((hieu sau) OR (hieu suat)) chat ((xuc va) or (duc va)) hanh thai cua tu*.