听力原文：M: Good morning. Can I help you? W: Hello. My name’s John Bush and I' m intending to go to a conference in Sydney for three weeks. M: I see. Do you want the excursion fare or the full return fare? W: Now, can I get a stopover on an excursion fare? M: Yes, you're allowed only one stopover on the excursion fare. W: Oh, I see, only one. M: Yes. But of course, if you pay the full return fare then you can have unlimited stopovers. W: Oh, it sounds good. You see, the thing is that I've got two weeks' holiday after the conference and I' ye never been out that way before at all to Australia or the Far East, and I want to go shopping or sightseeing in Hong Kong or somewhere near there. Where exactly can I go? M: Well, lots of places. There’s Singapore, Kuwait, Athens, you've really got quite a lot of choice you know. W: Mm. Well, it sounds marvelous. How much would that cost? How much is the full fare? M: The full fare? Well, that's really quite a lot. It's ￡ 1,204. W: Yes. Well, it’s once in a lifetime, you know, I've never been. The thing is actually that I' m absolutely afraid of flying. I've never done it before. M: Oh dear. Um... W: And I' m hoping that I can persuade my two friends, who are going to the conference, to stop over with me on the way back. M: Yes, that would be a good idea. W: By the way, one of them is in Cairo at the moment. Would it be possible for me to stop over there on my way to Sydney? M: Yes, of course. There are lots of flights to Cairo and, then plenty more onwards from Cairo to Sydney. And then you can stay for as long as you like. W: Oh, that’s great ! Now, the thing is, I think I' d better go and persuade Mr. Adams that, you know, he'd like to stop with me in Cairo... M: I see. W: Oh, thanks very much. Good-bye. M: Thank you. Good-bye. What is Mr. Bush's main purpose of the trip?