Perhaps you should try some spelling variations:
khanh thai » nhanh thai, khanh thanh, khanh thuan
van khanh » van thanh, van hanh, van anh
thai dua » thai cua, thi dua, thai doan
dua tren » dung tren
hieu ve » hieu va, hieu van
cac luc » cau luc, coc luc, cac nuoc
luc van » luoc van, luu van, duc van
ve cac » va cac, vien cac
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 cac ky nang ((o hoi) OR (o hai)). hieu ve cac luc van khanh thai dua tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu cac ky nang ((o hoi) OR (o hai)). hieu ve cac luc van khanh thai dua tren".
• Adding a wildcard symbol may retrieve word variants: tu cac ky nang ((o hoi) OR (o hai)). hieu ve cac luc van khanh thai dua tren*.