It was reported that the passenger ship was sailing eastwards in the Atlantic Ocean ____ its captain

and some passengers on board____ something supposed to be a UFO flying overhead.      [ ]

A. while; caught sight of                

B. when; caught sight of  

C. as; saw                            

D. since;  caught a sight of

企业通过期货市场销售和采购现货得到的最大的好处有( )。

A．严格履约

B．资金安全

C．库存降低

D．节约采购费用

E．保证数量

F．减少购货次数