表示原因的用语，例如：
　　The age of the product was a contributory factor in the accident.
　　预计结果用语，例如：
　　We can anticipate the following consequences:...
　　表示需要考虑，例如：　　Let us focus our attention on...
　　举例用语，例如
　　Here, I am just showing you a few examples of ...
　　展示胶片用语，例如：
　　Allow us, then, at this point to present some slides.
　　读报告的开场用语，例如：
　　My paper is a literature review.
　　提问用语，例如：　　My I ask a question? This is an extremely difficult question to answer.