知乎，让每一次点击都充满意义 —— 欢迎来到知乎，发现问题背后的世界。Top Hat dynamic eTexts are optimized for an interactive, Lively learning working experience. Educators can adopt—and adapt—any reserve to match the demands in their study course.这篇文章每月都会更新，可以收藏，如果对您有帮�