Henry was _____ struggling at sea by a British ship, _____ he was able to survive the accident.

A．spotted; and thus

B．discovered; thus

C．founded; so

D．seen; thus

根据票据交换理论，再多家银行参加的票据交换和清算的情况下，各行应收差额的综合一定（）各行应付差额的总和。

A、大于

B、小于

C、等

D、可能大于，也可能小于