Perhaps you should try some spelling variations:
hoc sach » hoc cac, hoc anh
cau tren » cu tren, dau tren, ca tren
ky sang » ky nang, ky dang, ky tang
sang ma » tang ma, nang ma, sang tao
va danh » va dinh, va dan, va hanh
danh vi » hanh vi, dinh vi, danh di
ma hoi » mai hoi, xa hoi, ma hoa
va cau » van cau, va cac, va dau
luc va » duc va, tuc va, loc va
vi cau » di cau, viet cau
ve cau » ke cau, ve cac, le cau

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((hoc sach) OR (hoc sinh)) ky sang ma hoi. hieu ((ve cau) or (va cau)) luc va danh vi cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((hoc sach) OR (hoc sinh)) ky sang ma hoi. hieu ((ve cau) OR (va cau)) luc va danh vi cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((hoc sach) OR (hoc sinh)) ky sang ma hoi. hieu ((ve cau) or (va cau)) luc va danh vi cau tren".
• Adding a wildcard symbol may retrieve word variants: ((hoc sach) OR (hoc sinh)) ky sang ma hoi. hieu ((ve cau) or (va cau)) luc va danh vi cau tren*.