Perhaps you should try some spelling variations:
khanh thi » nhanh thi, khanh thu, nhanh thai
van khanh » van thanh, van hanh, van anh
tu sach » thu sach, te sach, tu cach
thi cuc » tai cuc
vuc van » duc van, luc van, thuc van
cac vuc » cac nuoc, cac vung, cac cuoc
hieu ve » hieu va, hieu van
cuc tre » duc tre, cua tre, cuu tre
su sach » so sach, vu sach
ve cac » va cac, vien cac
y nang » ky nang, ly nang, v nang
o hoi » co hoi, o hoc, o hoa
o hai » co hai, so hai, o lai

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) OR (su sach)) y nang ((o hoi) or (o hai)). hieu ve cac vuc van khanh thi cuc tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) y nang ((o hoi) OR (o hai)). hieu ve cac vuc van khanh thi cuc tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (su sach)) y nang ((o hoi) or (o hai)). hieu ve cac vuc van khanh thi cuc tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (su sach)) y nang ((o hoi) or (o hai)). hieu ve cac vuc van khanh thi cuc tre*.