适用于在一定期限内分批发运、航程短、每批发运的货物基本相同且价值低的进出品货物的承保方式是（）。

A、逐笔保险

B、总括保险

C、流动保险

D、预约保险

The teacher _____ several times, but he still didn't understand it.[ ]

A. explained John the sentence            

B. explained the sentence for John

C. explained to John the sentence          

D. explained about the sentence to John