Perhaps you should try some spelling variations:
doan vi » doan va, don vi, doan thi
truc va » thuc va, thuc vat, trung va
ve cham » va cham, ve chat, vu cham
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
ky sang » ky nang, ky dang, ky tang
sac ky » cac ky, sai ky
tuc va » thuc va, tuc xa, duc va
vi cua » vai cua, di cua
tu sac » tu sach, tu cac, tu san

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sac ky sang ((xa hoi) or (ma hoa)). hieu ve cham ((tuc va) OR (truc va)) doan vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky sang ((xa hoi) OR (ma hoa)). hieu ve cham ((tuc va) OR (truc va)) doan vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sac ky sang ((xa hoi) or (ma hoa)). hieu ve cham ((tuc va) OR (truc va)) doan vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sac ky sang ((xa hoi) or (ma hoa)). hieu ve cham ((tuc va) OR (truc va)) doan vi cua tre*.