Annie Jump Cannon, ________ discovered so many stars that she was called "the census taker of the sky".

A．a leading astronomer,

B．who, as a leading astronomer,

C．was a leading astronomer,

D．a leading astronomer who

以下关于公共财政的基本特征，正确的有( )。

A．公共财政是弥补市场失灵的财政

B．公共财政的出发点和落脚点在于满足社会公共需要

C．公共财政的出发点和落脚点在于满足市场失灵

D．公共财政为市场提供一视同仁的服务

E．公共财政为市场提供有差别的服务