Once I invited a group of friends round to my house, telling them that I was going to record their speech. I said I was interested in their regional accents, and that it would take only a few minutes. Thus, on one evening, three people turned up at my house and were shown into my front room. When they saw the room they were a bit alarmed, for it was laid out as a studio. In front of each easy chair there was a microphone at head height, with wires leading to a tape-recorder in the middle of the floor. I explained that all I wanted was for them to count from one to twenty. Then we could relax and have a drink.
I turned on the tape-recorder and each in turn seriously counted from one to twenty in their best accent. When it was over, I turned the tape-recorder off and brought round the drinks, and for the rest of the evening there was general cheerful conversation—interrupted only by the fact that I had to take a telephone call in another room, which unfortunately lasted some time.
Or at least that was how it would appear. For, of course, the microphones were not connected to the tape-recorder in the middle of the room at all but to another one, which was turning happily away in the kitchen. The participants, having seen the visible tape-recorder turned off, paid no more attention to the microphones which stayed in front of their chairs, only a few inches from their mouths, thus giving excellent sound quality. And my lengthy absence meant that I was able to obtain as natural a piece of conversation as it would be possible to find.
I should add, perhaps, that I did tell my friends what had happened to them, after the event was over, and gave them the choice of destroying the tape. None of them wanted to—though for some years afterwards it always seemed to be my round when it came to the buying of drinks. Linguistic research can be a very expensive business.
The writer asked his friends to count from one to twenty because _______. 

A．he wanted to record the numbers for his research

B．he wanted to find out whether the tape recorder was working

C．he wanted to make his friends relax before real recording started

D．he wanted his friends to think that was all he wanted to record

The writer went into another room to ________.

A．get a natural recording of his friends’ conversation

B．stay away from too much drinking with his friends

C．bring a telephone into the front room

D．answer a long distance phone call

The writer turned off the tape-recorder because _______.

A．he had to answer a phone call

B．he wanted his friends to enjoy some drinks

C．he thought the tape-recorder might bother his friends

D．he wanted to make his friends believe he had finished the recording

Which one is true according to the passage?

A．The writer destroyed the tape.

B．The writer’s friends destroyed the tape.

C．The writer did tell his friends what had happened.

D．The writer’s friends like to drink.