Perhaps you should try some spelling variations:
cai tren » cai tien, ca tren, cau tren
caim luc » cau luc
hanh va » hanh vi
hieu va » lieu va, hieu qua
va caim » va cai, va cam, va chim
nang xa » lang xa, nang ma, mang xa
dan ky » van ky
luc va » duc va, tuc va, loc va
tu dan » tuc dan, tu ban, cu dan

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu dan ky ((nang xa) or (nang x)) hoi. hieu va caim luc va ((hanh va) OR (hang va)) cai tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu dan ky ((nang xa) OR (nang x)) hoi. hieu va caim luc va ((hanh va) OR (hang va)) cai tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu dan ky ((nang xa) or (nang x)) hoi. hieu va caim luc va ((hanh va) OR (hang va)) cai tren".
• Adding a wildcard symbol may retrieve word variants: tu dan ky ((nang xa) or (nang x)) hoi. hieu va caim luc va ((hanh va) OR (hang va)) cai tren*.