3. Add details. To write a more fully developed paragraph, you need to add details to your supporting ideas. Your details can be facts, examples, personal experiences, or descriptions.

　　（需要用多種方式提供細節展開段落。）

　　根據第3條的原則，我們來看下面這個段落：

　　The Smithsonian Institution is worth visiting for a number of reasons. The Smithsonian Institution comprises various museums that offer something for everyone. These museums include the National Museum of History and Technology, the National Aeronautics and Space Museum, the National Collection of Fine Arts, the National Museum of Natural History, and several others. A person can do more than just look at the exhibits. For example, in the insect zoo at the National Museum of Natural History, anyone who so desires can handle some of the exhibits. The museums provide unforgettable experiences. In climbing through the Skylab exhibit at the National Aeronautics and Space Museum, I was able to imagine what it would be like to be an astronaut in space. Movies shown at regular intervals aid in building an appreciation of our world. In the National Aeronautics and Space Museum, there is a theater that has a large screen. When the movie is shown, it gives the viewer the feeling that he or she is in the movie itself, either floating above the Earth in a hot-air balloon or hang gliding over cliffs.

　　這是一個成功的主題段，請注意這段話段落細節展開的幾種形式——提供事實、舉例、個人經歷和描述。我們把這個段落拆分后進行分析：

　　Topic sentence（主題句）

　　The Smithsonian Institution is worth visiting for a number of reasons.

　　Supporting idea 1（支持理由1）

　　The Smithsonian Institution comprises various museums that offer something for everyone.

　　Details -- facts（細節展開——提供事實）

　　These museums include the National Museum of History and Technology, the National Aeronautics and Space Museum, the National Collection of Fine Arts, the National Museum of Natural History, and several others.

　　Supporting idea 2（支持理由2）

　　A person can do more than just look at the exhibits.

　　Details -- examples（細節展開——舉例）

　　For example, in the insect zoo at the National Museum of Natural History, anyone who so desires can handle some of the exhibits.

　　Supporting idea 3（支持理由3）

　　The museums provide unforgettable experiences.

　　Details -- personal experience（細節展開——個人經歷）

　　In climbing through the Skylab exhibit at the National Aeronautics and Space Museum, I was able to imagine what it would be like to be an astronaut in space.

　　Supporting idea 4（支持理由4）

　　Movies shown at regular intervals aid in building an appreciation of our world.

　　Details -- description（細節展開——描述）

　　In the National Aeronautics and Space Museum, there is a theater that has a large screen. When the movie is shown, it gives the viewer the feeling that he or she is in the movie itself, either floating above the Earth in a hot-air balloon or hang gliding over cliffs.