Perhaps you should try some spelling variations:
hanh tai » thanh tai, hang tai, han tai
hanh lai » hanh lam, thanh lap, thanh loi
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
sach ky » sac ky, sach y, sach ty
ve cac » va cac, vien cac
cua te » cua tu
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 5 hoi

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 ((x hoi) OR (o hoi)). hieu ve cac nuoc va ((hanh lai) or (hanh tai)) cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((x hoi) OR (o hoi)). hieu ve cac nuoc va ((hanh lai) OR (hanh tai)) cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((x hoi) OR (o hoi)). hieu ve cac nuoc va ((hanh lai) or (hanh tai)) cua te".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((x hoi) OR (o hoi)). hieu ve cac nuoc va ((hanh lai) or (hanh tai)) cua te*.