Perhaps you should try some spelling variations:
vu khach » vu khanh, vay khach, cua khach
hieu van » hieu va, thien van, lieu va
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
vu khac » vu kham, vu khanh, bui khac
ky lang » ky nang, ky dang, ky tang
lang xa » lang ha, dang xay, lang van
van cac » van hac, van cau, van bac
va hanh » van hanh, va thanh, va danh
doi cua » dai cua, hoi cua, dong cua
di cua » dai cua, de cua, do cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((vu khach) or (vu khac)) ky lang xa hoi. hieu van cac nuoc va hanh ((di cua) OR (doi cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((vu khach) OR (vu khac)) ky lang xa hoi. hieu van cac nuoc va hanh ((di cua) OR (doi cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((vu khach) or (vu khac)) ky lang xa hoi. hieu van cac nuoc va hanh ((di cua) OR (doi cua)) tre".
• Adding a wildcard symbol may retrieve word variants: ((vu khach) or (vu khac)) ky lang xa hoi. hieu van cac nuoc va hanh ((di cua) OR (doi cua)) tre*.