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 cua » thai cua, thi cuc, tri cua
vuc van » duc van, luc van, thuc van
cac vuc » cac nuoc, cac vung, cac cuoc
hieu ve » hieu va, hieu van
cua tre » cua te, cuu tre, cua triet
su sach » so sach, vu sach
ve cac » va cac, vien cac
y nang » ky nang, ly nang, v nang
so hai » son hai, su hai, so ha
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: ((tu sach) or (su sach)) y nang ((o hoi) or (so hai)). hieu ve cac vuc van khanh thi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) y nang ((o hoi) OR (so hai)). hieu ve cac vuc van khanh thi cua tre.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) y nang ((o hoi) or (so hai)). hieu ve cac vuc van khanh thi cua tre*.