Perhaps you should try some spelling variations:
cau treo » cau theo, cau tren, cau triet
manh hai » lanh hai, minh hai, thanh hai
hieu van » hieu va, thien van, lieu va
nang ma » tang ma, sang ma, nang cao
van cau » van dau, van hau, van chat
truc va » thuc va, trung va
sach ty » sach tu, sach thu, xach tay
hai cau » hai chau, hai chu, hai hau
ma hoi » mai hoi, xa hoi, ma hoa

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 y) or (sach ty)) nang ma hoi. hieu van cau ((truc va) OR (thuc vat)) manh hai cau treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach y) OR (sach ty)) nang ma hoi. hieu van cau ((truc va) OR (thuc vat)) manh hai cau treo.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach y) or (sach ty)) nang ma hoi. hieu van cau ((truc va) OR (thuc vat)) manh hai cau treo".
• Adding a wildcard symbol may retrieve word variants: su ((sach y) or (sach ty)) nang ma hoi. hieu van cau ((truc va) OR (thuc vat)) manh hai cau treo*.