Perhaps you should try some spelling variations:
thuat sai » thuat bai, thuat san, thuat cai
dua tren » dung tren
hanh tai » thanh tai, hang tai, han tai
van hanh » van thanh, ban hanh, van anh
cac duc » cac du, cao duc, cac dac
duc van » duc va, duc tan, duc manh
qua cac » cua cac
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
sai ky » sac ky
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuat sai ky ((nang xa) OR (nang ma)) hoi. hieu qua cac duc van hanh tai ((dua tren) or (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat sai ky ((nang xa) OR (nang ma)) hoi. hieu qua cac duc van hanh tai ((dua tren) OR (cua te))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat sai ky ((nang xa) OR (nang ma)) hoi. hieu qua cac duc van hanh tai ((dua tren) or (cua te))*".