大全第一套第8题.

1.        A huge flying reptile that died out with the dinosaurs some 65 million years ago, the Quetzalcoatlus had a wingspan of 36 feet, believed to be the largest flying creature the world has ever seen.

(A) believed to be

(B) and that is believed to be

(C) and it is believed to have been

(D) which was, it is believed,（C）

(E) which is believed to be

第一次做的时候,我用排除法选择了C,但是不理解have been的用法.现在复习了,还是不明白!请赐教