legal ground
Article 42 of the Negotiable Instruments Law of People's Republic of China (PRC).
When accepting a bill of exchange, the drawee shall record the word "acceptance" and the date of acceptance on the front of the bill and sign it; A bill payable periodically after sight shall record the date of payment at the time of acceptance.
If the date of acceptance is not specified on the bill of exchange, the last day of the period specified in the first paragraph of the preceding article shall be the date of acceptance.
Article 43
The drawee shall unconditionally accept the bill of exchange; Conditional acceptance shall be deemed as refusal to accept.
Article 44
After accepting a bill of exchange, the drawee shall bear the responsibility for payment when due.