问题补充：
more careful, his ship would not have sunk.
A. If the captain were
B. Had the captain been
C. Should the captain be
D. If the captain would have been
答案：
A. If the captain were
(答案→)B. Had the captain been
C. Should the captain be
D. If the captain would have been
解析：因为由主句谓语可判断，表示的是与过去事实相反的情况，所以虚拟条件句中的谓语应用过去完成时，Had the captain been = If the captain had been。
