Perhaps you should try some spelling variations:
hoc nganh » hoc nhanh
hanh hai » thanh hai, nhanh hai, hang hai
hai cua » thai cua, dai cua, hoi cua
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
van hoi » van hoa, van hoc, van hoe
ky tang » ky nang, ky dang, kho tang
ky lang » ky nang, ky dang, tay lang
dac va » duc va, dat va, dai va
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: hoc nganh ((ky lang) OR (ky tang)) van hoi. hieu ve cac ((dac va) or (day va)) hanh hai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc nganh ((ky lang) OR (ky tang)) van hoi. hieu ve cac ((dac va) OR (day va)) hanh hai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc nganh ((ky lang) OR (ky tang)) van hoi. hieu ve cac ((dac va) or (day va)) hanh hai cua tre".
• Adding a wildcard symbol may retrieve word variants: hoc nganh ((ky lang) OR (ky tang)) van hoi. hieu ve cac ((dac va) or (day va)) hanh hai cua tre*.