Perhaps you should try some spelling variations:
thanh tai » thanh hai, thanh toan, doanh tai
duc manh » suc manh, duc anh, duc minh
quoc ban » quoc bao, quoc lan, quoc quan
cuc tre » duc tre, cua tre, cuu tre
hieu ve » hieu va, hieu van
hoc hai » hoc dai, hoc bai, hoc tai
sac ky » cac ky, sai ky
ve cac » va cac, vien cac
ho hai » pho hai, cho hai, ho hap
tu sac » tu sach, tu cac, tu san

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sac ky nang ((ho hai) OR (hoc hai)). hieu ve cac ((quoc ban) or (duc manh)) thanh tai cuc tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky nang ((ho hai) OR (hoc hai)). hieu ve cac ((quoc ban) OR (duc manh)) thanh tai cuc tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sac ky nang ((ho hai) OR (hoc hai)). hieu ve cac ((quoc ban) or (duc manh)) thanh tai cuc tre".
• Adding a wildcard symbol may retrieve word variants: tu sac ky nang ((ho hai) OR (hoc hai)). hieu ve cac ((quoc ban) or (duc manh)) thanh tai cuc tre*.