Perhaps you should try some spelling variations:
quyen tap » tuyen tap, luyen tap, quyen cap
thuc cong » thuoc cong, thu cong, chuc cong
cong cong » cong dong, trong cong, dung cong
luyen thi » nguyen thi
cac chat » cao chat, cac thuat, cac nha
cac khu » cac thu, cac khoi, cac kieu
ke y » ke o

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) or (luyen thi)) ((cac khu) or (cac chat)) đe co ban ((ke y) OR (ke ky)) thuc cong cong~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((quyen tap) OR (luyen thi)) ((cac khu) OR (cac chat)) đe co ban ((ke y) OR (ke ky)) thuc cong cong.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((quyen tap) or (luyen thi)) ((cac khu) or (cac chat)) đe co ban ((ke y) OR (ke ky)) thuc cong cong".
• Adding a wildcard symbol may retrieve word variants: ((quyen tap) or (luyen thi)) ((cac khu) or (cac chat)) đe co ban ((ke y) OR (ke ky)) thuc cong cong*.