Perhaps you should try some spelling variations:
dua tren » dung tren
thanh di » thanh doi, thanh de, thanh do
tu sach » thu sach, su sach, te sach
duc gia » quoc gia
cuu tre » cua tre, cau tren, cau treo
cao hoi » cau hoi, co hoi, cao hoc
y nang » ky nang, ly nang, v nang
ve cam » ve cham, va cam, ve cai
ve cac » va cac, vien 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 y nang cao hoi. hieu ((ve cam) OR (ve cac)) duc gia thanh di ((dua tren) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang cao hoi. hieu ((ve cam) OR (ve cac)) duc gia thanh di ((dua tren) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang cao hoi. hieu ((ve cam) OR (ve cac)) duc gia thanh di ((dua tren) or (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang cao hoi. hieu ((ve cam) OR (ve cac)) duc gia thanh di ((dua tren) or (cuu tre))*.