Perhaps you should try some spelling variations:
dat duoc » dat nuoc, da duoc, luat duoc
van hanh » van thanh, ban hanh, van anh
cua tre » cua te, cuu tre, cua triet
doi cua » dai cua, hoi cua
va hanh » va thanh, va danh, ban hanh
ma hanh » da hanh, na hanh, ban hanh
sang ma » tang ma, nang ma, sang tao
hieu ve » hieu va, hieu van
ky sang » ky nang, ky dang, ky tang
sac ky » cac ky, sai ky
ve dat » de dat, va dat, ve dao
ma hoi » mai hoi, xa hoi, ma hoa
va sac » va cac, va suc, va san

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

• Performing a fuzzy search may retrieve terms with similar spellings: va sac ky sang ma hoi. hieu ve dat duoc ((ma hanh) or (((va hanh) OR (van hanh)))) doi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: va sac ky sang ma hoi. hieu ve dat duoc ((ma hanh) OR (((va hanh) OR (van hanh)))) doi cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "va sac ky sang ma hoi. hieu ve dat duoc ((ma hanh) or (((va hanh) OR (van hanh)))) doi cua tre*".