Perhaps you should try some spelling variations:
nang cai » nang tai, nang cap, nang can
thanh vi » hanh vi, thanh va, thanh ve
so sanh » do sanh
qua cac » cua cac
cua tre » cua te, cuu tre, cua triet
sanh y » sinh y, anh y, hanh y
luc va » tuc va, loc va
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: so sanh y ((nang cai) or (nang cao)) hoi. hieu qua cac ((luc va) OR (duc va)) thanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sanh y ((nang cai) OR (nang cao)) hoi. hieu qua cac ((luc va) OR (duc va)) thanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sanh y ((nang cai) or (nang cao)) hoi. hieu qua cac ((luc va) OR (duc va)) thanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: so sanh y ((nang cai) or (nang cao)) hoi. hieu qua cac ((luc va) OR (duc va)) thanh vi cua tre*.