when the dispute over duty payment arises between the duty payer and the Customs, the duty payer should first pay the duty and then, within ______ days of the issuance of the duty memo, apply to the Customs in writing for a reconsidertation of the case.

A．10 days
B．20 days
C．30 days
D．50 days

煤田是指同一（）时期形成的，并大致连续发育的含煤岩系分布区，其面积一般由几十平方公里到几百平方公里。