Perhaps you should try some spelling variations:
luyen tap » tuyen tap, luyen thi
thuc dung » thuoc dung, thuy dung, thuat dung
cac chat » cao chat, cac thuat, cac nha
tuc dung » tac dung, duc dung, thuoc dung
tap cac » tai cac, tap trac
ban van » ban va, tan van, san van
ban dan » ban hang, ban hanh, ban quan

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

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