Perhaps you should try some spelling variations:
dieu cua » dieu tra
vanh dai » van dai, vanh tai, lanh dao
nang xa » nang x, nang ma, mang xa
lang xa » lang ha, dang xay, lang van
cac hoc » cach hoc, cac hop, bac hoc
va vanh » va van, va danh, va hanh
te sac » te sach, te cac, te san
sac ky » cac ky, sai ky
cua tu » cua tuc, cua su, cua te
cua cu » cua chu, cua cau, cua su

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sac ky ((nang xa) or (lang xa)) hoi. dieu cua cac hoc va vanh dai ((cua tu) or (cua cu))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sac ky ((nang xa) OR (lang xa)) hoi. dieu cua cac hoc va vanh dai ((cua tu) OR (cua cu)).
• Adding a wildcard symbol may retrieve word variants: te sac ky ((nang xa) or (lang xa)) hoi. dieu cua cac hoc va vanh dai ((cua tu) or (cua cu))*.