The irrevocable L/C can（）.

A．be amended or canceled without notice to the beneficiary

B．be amended or canceled if the buyer notifies the seller

C．neither be amended nor canceled without agreement of all parties

D．be amended but not be canceled by an applicant

下列属于公文文尾部分的是（）。

A.主题词

B.附件

C.印章

D.成文时间