Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
tu sach » thu sach, te sach, tu cach
su sach » so sach, vu sach
cao hoi » cau hoi, co hoi, cao hoc
ve pham » vi pham, v pham, ve phat
ve phan » va phan, ke phan, ve phat
thuc va » thuc vat, thuc dan, thuc day
va dan » ca dan, va dao, va dau
ca cau » cua cau, cac cau, can cau

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

• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ky nang cao hoi. hieu ((ve pham) OR (ve phan)) thuc va dan ca cau tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (su sach)) ky nang cao hoi. hieu ((ve pham) OR (ve phan)) thuc va dan ca cau tren~".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) ky nang cao hoi. hieu ((ve pham) OR (ve phan)) thuc va dan ca cau tren*.