Perhaps you should try some spelling variations:
nang dau » hang dau, xang dau, nang du
thanh de » hanh de, thanh ve, thanh le
thanh do » thanh pho, thanh hoa, thanh loi
tu sach » thu sach, su sach, te sach
dau hoi » cau hoi, dai hoi, dan hoi
hieu ve » hieu va, hieu van
cac dac » cac dan, cac dai, cac bac
cuu tre » cua tre, cau tren, cau treo
y nang » ky nang, ly nang, v nang
ve cac » va cac, vien cac
dac va » duc va, day va, dat va

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 dau hoi. hieu ve cac dac va ((thanh de) or (thanh do)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang dau hoi. hieu ve cac dac va ((thanh de) OR (thanh do)) cuu tre.
• Adding a wildcard symbol may retrieve word variants: tu sach y nang dau hoi. hieu ve cac dac va ((thanh de) or (thanh do)) cuu tre*.