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.
