Perhaps you should try some spelling variations:
cac truc » cau truc, cac tru, cac trung
hanh vai » hanh vi, hanh va, hanh tai
truc va » thuc va, thuc vat, trung va
cua tre » cua te, cua triet, dua tren
va hanh » van hanh, va thanh, va danh
bo sach » co sach, hoc sach
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma
cuu tre » cau tren, cau treo

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

• Performing a fuzzy search may retrieve terms with similar spellings: bo sach y ((nang xa) or (nang cao)) hoi. hieu va cac truc va hanh vai ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: bo sach y ((nang xa) OR (nang cao)) hoi. hieu va cac truc va hanh vai ((cua tre) OR (cuu tre)).
• Adding a wildcard symbol may retrieve word variants: bo sach y ((nang xa) or (nang cao)) hoi. hieu va cac truc va hanh vai ((cua tre) or (cuu tre))*.