参考答案：C

解析：[听力原文] 29-31
One of Britain’s few distinctive contributions to world culture may be doomed, according to a survey that suggests (29)holiday postcards are being emailed and texted into extinction. More than half of the 1,000 holidaymakers interviewed said they had decided to send fewer cards, turning instead to their electronic rivals. A quarter of the respondents dismissed postcards as old-fashioned and slow to arrive. A further 14% admitted that thinking of something to fill the space was too challenging, compared with a call home.
Thomson Holidays commissioned the poll. Its head, Chris Motters said that if the British postcard did become extinct, they would lose for ever something of great importance to the nation. He was backed by Marie Angelou of Sussex University, who has investigated the importance of sending and receiving postcards. (30) "Postcards are nothing like phone calls, instant texting and direct photo shots via the mobile," she said. "All these are useful, practical devices, but postcards offer something else, something additional that is not mundane and simply functional, but imaginative and personal. They can evoke the real atmosphere of your holiday in a way that nothing else can do. They’re also for more than a moment -- with some people adding them to collections built up over years and years."
(31) Postcard-collecting, is third only to coins and stamps in Britain’s allied tradition of collecting things. The country’s uniquely postcard-related achievements include the invention in 1902 of the "divided back". With the address taking up half of the writing area, brief postcard scribbles became the pioneer to today’s text messages.
29．What’s the main idea of this passage

[听前猜测] 四个选项都是在说不同的通讯手段的发展趋势，推测本题提问文章的主题。
[精解] 文章一开始说收到节日明信片的人越来越少，随后对明信片的意义进行阐述，最后对明信片可能消失的命运感叹。因此，文章的主题是明信片将在人们的生活中消失，故本题答案为C)。