HSK 4
Yuánzéshàng wǒmen tóngyì zhège fāng'àn.
In principle we agree to this proposal.
HSK 7-9
Yuánzéshàng bùnéng tuìkuǎn, dàn kěyǐ huànhuò.
As a rule refunds aren't allowed, but exchanges are fine.
HSK 7-9
Yuánzéshàng měirén xiàn mǎi liǎng zhāng.
In principle each person may buy two tickets at most.