Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
hanh di » hanh vi, hanh de, hang di
cac ban » cac dan, cac van, can ban
cuc ban » cua ban, cuu ban, duc ban
te sach » toc sach
hieu ve » hieu va, hieu van
su sach » so sach, vu sach
nang o » nang co, nang ho, nang ro
di cau » da cau, diem cau
ve cac » va cac, vien cac
o hoi » co hoi, o hoc, o hai

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) or (su sach)) ky nang o hoi. hieu ve cac ((cuc ban) or (cac ban)) hanh di cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (su sach)) ky nang o hoi. hieu ve cac ((cuc ban) OR (cac ban)) hanh di cau tren.
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (su sach)) ky nang o hoi. hieu ve cac ((cuc ban) or (cac ban)) hanh di cau tren*.