Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
than tai » thanh tai, toan tai, nhan tai
thuc dan » thuc hanh, hoc dan, thuc vat
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
han tai » hang tai, nhan tai, van tai
san ky » sang ky, van ky, ban ky
va nam » van nam, ha nam, va nay
dan ky » van 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: toc ((san ky) OR (dan ky)) nang xa hoi. hieu va nam thuc dan ((han tai) or (than tai)) cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc ((san ky) OR (dan ky)) nang xa hoi. hieu va nam thuc dan ((han tai) OR (than tai)) cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc ((san ky) OR (dan ky)) nang xa hoi. hieu va nam thuc dan ((han tai) or (than tai)) cua te".
• Adding a wildcard symbol may retrieve word variants: toc ((san ky) OR (dan ky)) nang xa hoi. hieu va nam thuc dan ((han tai) or (than tai)) cua te*.