Perhaps you should try some spelling variations:
thien van » thi van
thuc dan » thuc hanh, hoc dan
dau tren » dau tien, dat tren, dau tieng
hieu ve » hieu va, hieu van
danh vi » hanh vi, dinh vi, danh di
su xac » pu xac, su cac
xac ky » cac ky, sac ky, bac ky
vi dau » vi dai, va dau, bi dau
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: su xac ky nang x hoi. ((hieu ve) or (thien van)) nam ((thuc dan) or (thuc vat)) danh vi dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su xac ky nang x hoi. ((hieu ve) OR (thien van)) nam ((thuc dan) OR (thuc vat)) danh vi dau tren.
• Adding a wildcard symbol may retrieve word variants: su xac ky nang x hoi. ((hieu ve) or (thien van)) nam ((thuc dan) or (thuc vat)) danh vi dau tren*.