Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
hanh lai » hanh lam, hanh tai, thanh lap
thuc dan » thuc hanh, hoc dan, thuc vat
thuc va » thuc vat, thuc day
doc sac » doc sach, dac sac, hoc sach
hieu vi » hieu voi, hieu ve, hien vi
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
sac ky » cac ky, sai ky
ma hoi » mai hoi, xa hoi, ma hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sac ky nang ma hoi. ((hieu vi) OR (hieu va)) pham ((thuc va) or (thuc dan)) hanh lai su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sac ky nang ma hoi. ((hieu vi) OR (hieu va)) pham ((thuc va) OR (thuc dan)) hanh lai su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sac ky nang ma hoi. ((hieu vi) OR (hieu va)) pham ((thuc va) or (thuc dan)) hanh lai su triet".
• Adding a wildcard symbol may retrieve word variants: doc sac ky nang ma hoi. ((hieu vi) OR (hieu va)) pham ((thuc va) or (thuc dan)) hanh lai su triet*.