Perhaps you should try some spelling variations:
danh vai » danh sai, danh va, doanh van
hieu van » hieu va, thien van, lieu va
truc va » thuc vat, trung va
vai cua » dai cua, hai cua, lai cua
thuc va » thuc vat, thuc dan, thuc day
van cau » van dau, van hau, van chat
sach ky » sach y, sach ty, sach kem
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, cua triet
sac ky » cac ky, sai ky

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

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach ky) or (sac ky)) nang xa hoi. hieu van cau ((truc va) OR (thuc va)) danh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sac ky)) nang xa hoi. hieu van cau ((truc va) OR (thuc va)) danh vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ky) or (sac ky)) nang xa hoi. hieu van cau ((truc va) OR (thuc va)) danh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) or (sac ky)) nang xa hoi. hieu van cau ((truc va) OR (thuc va)) danh vai cua tre*.