Perhaps you should try some spelling variations:
thuc dan » thuc hanh, hoc dan, thuc vat
hieu va » lieu va, hieu qua
thuc va » thuc vat, thuc day
tang ma » mang may, tang van
vi cua » vai cua, di cua
cai ky » cao ky, cam ky, sai ky
ma hoi » mai hoi, xa hoi, ma hoa
cua te » cua tu
va am » va lam, va cam

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

• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((cai ky) OR (cac ky)) tang ma hoi. hieu va am ((thuc va) OR (thuc dan)) hanh vi cua te~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((cai ky) or (cac ky)) tang ma hoi. hieu va am ((thuc va) OR (thuc dan)) hanh vi cua te~".
• Adding a wildcard symbol may retrieve word variants: tu ((cai ky) or (cac ky)) tang ma hoi. hieu va am ((thuc va) OR (thuc dan)) hanh vi cua te*.