A、Basing them on science-fiction movies. B、Including interesting examples in them. C、Adjusting them to different audiences. D、Fo

When US spacewoman Joan Higginbotham is not flying and working in space, she might be found somewhere on earth giving a speech. Higginbotham, who grew up in Chicago and became an engineer before joining NASA, that is the National Air and Space Administration, gives about a dozen speeches a year. Each speech is different because she tailors her remarks to each audience. Through interviews and E-mails, she finds out in advance her listeners’ educational level and what information they want to know. On the subject of space walks, for example, audiences vary in their interests and how much complexity they can comprehend. To elementary school children, Higginbotham may discuss a problem that many kids want to know about. "How do spacemen in a spacesuit eat, drink, and go to the bathroom?" Her answer is "the spacesuit is really a small spacecraft with room for food and water-containers, and a waste-collection system." To a high school audience, she might satisfy a curiosity that often arises in her pre-speech interviews with students who obviously have seen many science fiction movies. "Do spacemen carry weapons in case they encounter enemies in space?" Her answer is "No". To scientists, she might provide technical details on such topics as the design of spacesuits that protects spacemen from the deadly temperature extremes of space. Just as elaborate preparation is required for success in space, Higginbotham says that it’s important for speakers to learn as much as possible about their listeners before a speech because every audience is different.
Questions 20 to 22 are based on the passage you have just heard.
20. What did Joan Higginbotham do before joining in NASA?
21. How does Higginbotham prepare her speech on space walks?
22. What does the high school audience want to know about space travel?