企业在货物出口报关后，应在中国口岸执法系统进行网上交单，待收汇后，可凭（）等有效凭证一并到外汇局办理核销手续。

A、信用证

B、纸质出口收汇核销单

C、出口报关单

D、贸易合同

E、银行出具的出口收汇专用联

--- Don’t do that again. Don’t you think it _______?

--- It maybe _______ to be successful.

A．a waste of time; turns

B．wastes of time; turns in

C．waste of time; turns up

D．a waste of time; turns out