A、Improve spoken English. B、Sharpen listening ability. C、Enlarge idiom vocabulary. D、Improve writing skills. D细节题。对话中依次列举了三点好处，

W: Wu, do you have time to tell me more about the multimedia teaching system?
M: Oh, yes, sure. The system is basically a computer system plus the projector, the slide and some other output equipment. They key point is the software.
W: The software?
M: Mm, only by using good software, can this system give us a good authentic English speaking environment.
W: But how does it do that?
M: The system and the software do more than offering English learners visual and audio exposure to the native language. They invite the learner to become part of the "oral class" where the learner is immersed in the conversations of native speakers in everyday situations.
W: So the learner’ s participation is important?
M: Of course. The participation can be in 2 major ways. First, learners can correct their pronunciations and intonations at the beginning stages of English learning. They can record their spoken English into the computer and then compare that with the built-in teacher’ s voice.
W: Sounds interesting.
M: Yes. And the communicative ability of the student is also heightened by role-playing in various situations and talking with different English speakers.
W: I think in this way the benefit for the English learner does not stop at the improvement of their spoken English.
M: Exactly. They will also sharpen their listening ability and enlarge their idiom vocabulary at the same time.
W: If the system can really be spread on the campus, our English will be improved greatly. I’ m looking forward to that.
M: I think that’ s coming in the near future.
Questions 12 to 15 are based on the conversation you have just heard.
12. What can give learners a good authentic English speaking environment?
13. What situation does the teaching system invite people to get involved?
14. What is not the benefit of this system?
15. What is the main idea of this conversation?