Perhaps you should try some spelling variations:
hanh tai » thanh tai, hang tai, han tai
thuc dan » thuc hanh, hoc dan, thuc vat
sach ky » sach y, sach ty, sach kem
thuc va » thuc vat, thuc day
su tien » su kien, su hien, tu tieng
hieu ve » hieu va, hieu van
nang o » nang co, nang ho, nang ro
sac ky » cac ky, sai ky
tai su » tai so, tai tu, lai su
ve cam » ve cham, ve cac, va cam
o hoi » co hoi, o hoc, o hai

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

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