The number 9.11 is a special number I think that will be remembered by the Americans f

问题补充：

The number 9.11 is a special number, , I think, that will be remembered by the Americans forever.

A. what

B. it

C. which

D. one

答案：

1A. what1B. it1C. which1D. one1解析：考查代词。one作number的同位语。