Perhaps you should try some spelling variations:
cac viet » cach viet, bac viet, ca viet
dinh tai » dinh toai, dinh tri, dinh thi
tai cac » tai cuc
thuc va » thuc vat, thuc dan, thuc day
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
va cam » va cham, va cac, va cao
tuc va » truc va, tuc xa, duc va
tu can » tu ban, tu cac, thu canh
tu san » thu san, tu ban, vu 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 san) or (tu can)) ky nang xa hoi. hieu va cam ((tuc va) OR (thuc va)) dinh tai cac viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu san) OR (tu can)) ky nang xa hoi. hieu va cam ((tuc va) OR (thuc va)) dinh tai cac viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu san) or (tu can)) ky nang xa hoi. hieu va cam ((tuc va) OR (thuc va)) dinh tai cac viet".
• Adding a wildcard symbol may retrieve word variants: ((tu san) or (tu can)) ky nang xa hoi. hieu va cam ((tuc va) OR (thuc va)) dinh tai cac viet*.