A、The common sense. B、The subject matter. C、The start of the report. D、The understanding of listeners. B讲座最后提到新闻展现的风格需与新闻主题匹配，故B

News can be something the authorities want you to know, or something they would rather keep secret. An announcement of a government success, a denial of a failure, or, a secret scandal that nobody really wants you to talk about.
    If the authorities want to tell the world some good news, they issue statements and call press conferences. Or politicians make speeches. Local newspapers, radio and television help to alert foreign correspondents to what is going on. And by making contacts with local officials, journalists can ask for more information or explanation to help them write their stories. Unless the correspondent is an eyewitness, it’s rare to trust any single source. Officials have a policy to defend, and opposition politicians want to attack it. Rumor and gossip can also confuse the situation. So, you have to check information as much as possible using common sense and experience as final checks to help establish just what’s likely to be the truth, or close to it.
    Just getting the news is only half the job. A correspondent may be well-informed, but his job is to inform other people, the public. So once the information is available it has to be written in an interesting way which is also easily understood. Particularly for radio, since, while a newspaper reader can turn back and re-read a sentence or two, the radio listener has only one chance. This also means that only a limited number of facts can be contained in a sentence, that there should be an element of repetition. And vital information necessary to understand the latest development should be presented at the start of a report—in case the producer of a news program decides to shorten an item, by cutting for example the last sentence or two. Finally, the style of presentation must match the subject matter. A cheerful voice might be perfect for a royal wedding. But it would be sadly out of place for a report of a plane crash. And this would also confuse and distract the listener, probably making it difficult to understand just what had happened and to whom.
20. What will authorities do if they want to tell the world some good news?
21. What is a correspondent’s main job?
22. What does the style of presentation have to match?