I worked on the problem ____ a long time and I worked it out ____ myself ____ last.[ ]

A. for; by; at

B. in; with; on

C. on; by; in

D. for; for; at the

出口打包贷款是( )凭进口商所在地银行开立的信用证及该信用证项下的出口商品为抵押向出口商提供的短期贷款。

A．出口商

B．出口商当地的银行

C．进口商

D．进口商当地的银行