Perhaps you should try some spelling variations:
nang doc » nang luc
nang ro » nang co, nang ho, nang ra
hieu ve » hieu va, hieu van
cac thu » cach thuc, cac thoi
cua tre » cua te, cuu tre, cua triet
te sac » te sach, te cac, te san
sac ky » cac ky, sai ky
nang o » nang co, nang ho, nang x
ve cac » va cac, vien cac
thu va » thuc va, thue va, tu va
va don » va dong, va doc, va do
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sac ky ((((nang o) or (nang doc))) or (nang ro)) hoi. hieu ve cac thu va don vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sac ky ((((nang o) OR (nang doc))) OR (nang ro)) hoi. hieu ve cac thu va don vi cua tre.
• Adding a wildcard symbol may retrieve word variants: te sac ky ((((nang o) or (nang doc))) or (nang ro)) hoi. hieu ve cac thu va don vi cua tre*.