Perhaps you should try some spelling variations:
quyen tap » tuyen tap, luyen tap, quyen cap
cach thuc » anh thuc
cong cong » cong dong, trong cong, dung cong
thi cong » tai cong, thien cong
cac chu » cac che, cac khu, ca chu
cac thu » cac thoi
ban vem » ban kem, ban viet
ban ve » ban va
y thi » ky thi, y thai, ly thi

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

• Performing a fuzzy search may retrieve terms with similar spellings: quyen tap ((cac chu) or (((cach thuc) OR (cac thu)))) đe co ((ban vem) or (ban ve)) y thi cong cong~.
• If you are trying to use Boolean operators, they must be ALL CAPS: quyen tap ((cac chu) OR (((cach thuc) OR (cac thu)))) đe co ((ban vem) OR (ban ve)) y thi cong cong.
• The words AND, OR and NOT may confuse the search; try adding quotes: "quyen tap ((cac chu) or (((cach thuc) OR (cac thu)))) đe co ((ban vem) or (ban ve)) y thi cong cong".
• Adding a wildcard symbol may retrieve word variants: quyen tap ((cac chu) or (((cach thuc) OR (cac thu)))) đe co ((ban vem) or (ban ve)) y thi cong cong*.