Be sure you don't change the subject in the middle of a paragraph, and be sure that everything under one heading in your outline is about the same general topic.
确定你并没有在段落途中改变主题，同时也确定在你的大纲中那些属于同个标题的内容都关乎同个主题。
2
That means heading into unfamiliar territory, for the properties of materials change when devices are just nanometres across.