Perhaps you should try some spelling variations:
thanh tay » thanh tai, thanh toan, thanh thuy
thuc day » thuc dan, thuc vat
thuc va » thuc vat, thuc dan
tay cua » day cua, ty cua
bach ky » bac ky
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
va can » va chan, va cac, va cao
o hai » co hai, so hai, o lai
o hoi » co hoi, o hoc, o hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu bach ky nang ((o hoi) or (o hai)). hieu va can ((thuc va) OR (thuc day)) thanh tay cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu bach ky nang ((o hoi) OR (o hai)). hieu va can ((thuc va) OR (thuc day)) thanh tay cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu bach ky nang ((o hoi) or (o hai)). hieu va can ((thuc va) OR (thuc day)) thanh tay cua tre".
• Adding a wildcard symbol may retrieve word variants: vu bach ky nang ((o hoi) or (o hai)). hieu va can ((thuc va) OR (thuc day)) thanh tay cua tre*.