Perhaps you should try some spelling variations:
tren luyen » trinh luyen, tien quyen, tre tuyen
kin tren » dinh tren, gian tren, sinh tren
luyen ky » truyen ky, luyen de
nang ma » tang ma, sang ma, nang cao
ky sang » ky tang, duy sang
ky dang » ky danh
bi kin » bai kinh
tuoi 7 » tuoi 1
bo bi » bao bi, bo bai, so bi
bot » both

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( bot bi kin tren luyen ky nang ma. Đo tuoi 7-15 ) or ( bo bi kip ren luyen ((ky sang) OR (ky dang)) ma. Đo tuoi 7-15 ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( bot bi kin tren luyen ky nang ma. Đo tuoi 7-15 ) OR ( bo bi kip ren luyen ((ky sang) OR (ky dang)) ma. Đo tuoi 7-15 )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( bot bi kin tren luyen ky nang ma. Đo tuoi 7-15 ) or ( bo bi kip ren luyen ((ky sang) OR (ky dang)) ma. Đo tuoi 7-15 ))".
• Adding a wildcard symbol may retrieve word variants: (( bot bi kin tren luyen ky nang ma. Đo tuoi 7-15 ) or ( bo bi kip ren luyen ((ky sang) OR (ky dang)) ma. Đo tuoi 7-15 ))*.