Perhaps you should try some spelling variations:
quoc quan » qua quan, luc quan, hoc quan
lang mai » lang dai, lang hai, lang man
quoc ban » quoc bao, quoc lan, quoc binh
hanh tai » thanh tai, hang tai, han tai
ky lang » ky nang, ky dang, ky tang
mai hoi » mai khoi, dai hoi, lai hoi
hieu va » lieu va, hieu qua
va chat » van chat, va phat, cao chat
tai cua » thai cua, tai cuc, tri cua
tu sac » tu sach, tu cac, tu san
sac ky » cac ky, sai ky
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sac ky lang mai hoi. hieu va chat ((quoc ban) or (quoc quan)) hanh tai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky lang mai hoi. hieu va chat ((quoc ban) OR (quoc quan)) hanh tai cua te.
• Adding a wildcard symbol may retrieve word variants: tu sac ky lang mai hoi. hieu va chat ((quoc ban) or (quoc quan)) hanh tai cua te*.