Perhaps you should try some spelling variations:
va thanh » gia thanh, ban thanh, le thanh
dang cau » hang cau, bang cau, dang mau
tu sach » thu sach, su sach, te sach
cuc tre » cua tre, cuu tre, cuc thue
va tinh » may tinh
duc tre » duoc tren, duc tien
sach ky » sac ky, sach y, sach ty
cau luc » cau truc, cau phuc
hieu ve » hieu va, hieu van
ky dang » ky nang, ky danh
ve cau » ke cau, va cau, ve cac

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 dang cau hoi. hieu ve cau luc ((va thanh) or (va tinh)) tai ((cuc tre) OR (duc tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky dang cau hoi. hieu ve cau luc ((va thanh) OR (va tinh)) tai ((cuc tre) OR (duc tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky dang cau hoi. hieu ve cau luc ((va thanh) or (va tinh)) tai ((cuc tre) OR (duc tre))".
• Adding a wildcard symbol may retrieve word variants: tu sach ky dang cau hoi. hieu ve cau luc ((va thanh) or (va tinh)) tai ((cuc tre) OR (duc tre))*.