Perhaps you should try some spelling variations:
nuoc gia » nuoc giai, nuoc giao, quoc gia
mai hoi » mai khoi, dai hoi, lai hoi
hieu ve » hieu va, hieu van
vu dai » vi dai, va dai, vu hai
dai ky » dan ky, dai ly, sai ky
ve hoc » te hoc, va hoc, vi hoc
vi cua » vai cua
di cua » dai cua, doi cua, de cua

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

• If you are trying to use Boolean operators, they must be ALL CAPS: vu dai ky nang ((mai hoi) OR (ma hoa)). hieu ve hoc nuoc gia thanh ((vi cua) OR (di cua)) tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu dai ky nang ((mai hoi) or (ma hoa)). hieu ve hoc nuoc gia thanh ((vi cua) OR (di cua)) tre~".
• Adding a wildcard symbol may retrieve word variants: vu dai ky nang ((mai hoi) or (ma hoa)). hieu ve hoc nuoc gia thanh ((vi cua) OR (di cua)) tre*.