1、引出开篇类：Recently the problem of…… has been brought into focus. ==Nowadays there is a growing concern over ……(最近……问题引起了关注)。

2、提出建议类：There is no doubt that enough concern must be paid to the problem of……(毫无疑问，对……问题应予以足够重视)。

3、故事引出类：I have a friend who ... Should he....? Such a dilemma we are often confronted with in our daily life.

4、表达不同观点类：Peoples views on……vary from person to person. Some hold that……However, others believe that……(人们对……的观点因人而异，有些人认为……然而其他人却认为……)

5、预示后果类：Obviously，if we dont control the problem, the chances are that……will lead us in danger.(很明显，如果我们不能控制这一问题，很有可能我们会陷入危险)。