一、单选题（共 25 道试题，共 50 分。）V
1. _________ the earth to be flat, many feared that Columbus would fall off the edge of the earth.
A. having believed
B. believing
C. believed
D. being believed
满分：2 分
2.
--Thanks for your help.
--____________.
A. My pleasure.
B. Never mind.
C. Quite right.
D. Don’t thank me.
满分：2 分
3.
Did you use to play the piano?
- _____________________
A. Yes, I do.
B. No, I didn't.
C. Yes, I play it every day.
D. No, I do.
满分：2 分
4. Government reports, examination compositions, legal documents and most business letters are the main situations_____ formal language is used.
A. in which
B. at what
C. on which