Perhaps you should try some spelling variations:
dang khoi » dung khoa, hang khoa
duc tien » duc thien, luc tieng, thuc tien
chat duc » chat xuc, chat doc, chet duoc
dang thi » hoang thi
duc toan » duc tan, duc ton, duc hoan
va chat » van chat, va phat, cao chat
hieu va » lieu va, hieu qua
dang xa » dang xay, lang xa, dang ha
dai ky » dan ky, sai ky

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

• Performing a fuzzy search may retrieve terms with similar spellings: su ((dai ky) or (dai ly)) dang xa hoi. hieu va chat duc toan ((dang thi) or (dang khoi)) duc tien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((dai ky) OR (dai ly)) dang xa hoi. hieu va chat duc toan ((dang thi) OR (dang khoi)) duc tien.
• Adding a wildcard symbol may retrieve word variants: su ((dai ky) or (dai ly)) dang xa hoi. hieu va chat duc toan ((dang thi) or (dang khoi)) duc tien*.