Perhaps you should try some spelling variations:
vien cac » vien bach, vien dai, vien da
hai cua » thai cua, dai cua, hoi cua
vai cua » dai cua, lai cua, bai cua
xa hanh » xa thanh, xa khanh, va hanh
tu can » tu ban, tu cac, thu canh
can ky » van ky, dan ky, ban ky
ve cac » va cac
nang o » nang co, nang ho, nang ro
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 can ky nang o hoi. hieu ((ve cac) OR (vien cac)) tuc xa hanh ((vai cua) or (hai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu can ky nang o hoi. hieu ((ve cac) OR (vien cac)) tuc xa hanh ((vai cua) OR (hai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu can ky nang o hoi. hieu ((ve cac) OR (vien cac)) tuc xa hanh ((vai cua) or (hai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: tu can ky nang o hoi. hieu ((ve cac) OR (vien cac)) tuc xa hanh ((vai cua) or (hai cua)) tre*.