Perhaps you should try some spelling variations:
cach thoi » cac thoi, cach thuc, cach noi
thoi nang » thi nang, hoi nang, khoi nang
hieu quan » lieu quan, thien quan, lien quan
dan hanh » dang hanh, dan khanh, dan thanh
thuc dan » thuc hanh, hoc dan, thuc vat
tu cach » tu cac
hanh di » hanh vi, hanh de, hang di
ca viet » va viet, co viet, hoa viet
hieu ve » hieu va, hieu van
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa
di ca » di cau, di cua, doi ca

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu cach thoi nang ma hoi. ((((hieu quan) or (hieu ve))) or (hieu qua)) am thuc dan hanh di ca viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu cach thoi nang ma hoi. ((((hieu quan) OR (hieu ve))) OR (hieu qua)) am thuc dan hanh di ca viet.
• Adding a wildcard symbol may retrieve word variants: tu cach thoi nang ma hoi. ((((hieu quan) or (hieu ve))) or (hieu qua)) am thuc dan hanh di ca viet*.