Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
van chat » cao chat
toc sac » toc sach, toc san, doc sach
nang xa » nang x, lang xa, nang ma
hieu ve » hieu va, hieu van
va danh » va dinh, va dan, va hanh
van cau » van dau, van hau, toan cau
ve cau » ke cau, va cau, ve cac

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

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