Perhaps you should try some spelling variations:
nang tai » hang tai, tang tai, sang tai
thuc dan » thuc hanh, hoc dan, thuc vat
thuat va » thuyet va, thuat xay, thuat bai
tu sach » thu sach, su sach, te sach
tai cua » thai cua, tai cuc, tri cua
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
va cam » va cham, va cac, va cai
ma hoi » mai hoi, xa hoi, ma hoa
va cao » va cac, va co, va dao

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 nang ma hoi. hieu ((va cam) OR (va cao)) ((thuat va) or (thuc dan)) nang tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ma hoi. hieu ((va cam) OR (va cao)) ((thuat va) OR (thuc dan)) nang tai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ma hoi. hieu ((va cam) OR (va cao)) ((thuat va) or (thuc dan)) nang tai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ma hoi. hieu ((va cam) OR (va cao)) ((thuat va) or (thuc dan)) nang tai cua tre*.