Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
thu sach » thuat sach, thuoc sach, thu hoach
thuc va » thuc vat, thuc dan, thuc day
hieu ve » hieu va, hieu van
tu sach » su sach, te sach, tu cach
cao hoi » cau hoi, co hoi, cao hoc
tuc va » truc va, tuc xa, duc va
ca cau » cua cau, cac cau, can cau
ve cam » ve cham, ve cac, va cam

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

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