A、  B、  C、  A题目为询问罗伯茨先生是如何得知研究的How疑问句。

Our clients have already been to the factory, haven’t they?
(A) No, I don’t believe so.
(B) Production started last week.
(C) In just a few minutes.

How did Mr. Roberts learn about our research?
(A) Through a Web site.
(B) About health products.
(C) I completed the survey.