—do you know so much about the UFO?—I usually get the information by surfing the Internet.

问题补充：

—do you know so much about the UFO?

—I usually get the information by surfing the Internet.

A. How

B. What

C. Which

D. Where

答案：

(答案→)A. How

B. What

C. Which

D. Where

解析：How如何，怎样；What什么；Which哪一个；Where在哪儿。根据下文，我通常通过上网来获得信息。可知上文问的是，关于飞碟，你是如何知道这么多的？故选A。