采取分期付款方式销售货物时，其增值税专用发票开具的时限是( )。

A．货物发出的当天

B．收到第一期销售额的当天

C．合同约定的收款日期的当天

D．收到全部货款的当天

Einstein liked Bose’s paper so much that he ___ his own work and translated it into German.

A．gave off

B．turned down

C．took over

D．set aside