开题：描述的方式来引出要议论的主题。
以叙代议 常见：
As we can see , has become a very important problem in the rapidly developing world.
Adimttedly, has attracted more and more attention from people.
As we know. Bring us many b123fits and conviences.
Judging from that fact, it is very obvious thathas become part of our everyday life to some extent.
The emergence of is really worth our respect in history while it still remains meaningful to us now.
个人描述：以个人的亲身经历来引起要议论的问题。
Once, I had the experience of
I can never forget the experience of
Personally, at first sight of this topic, I could not help thinking about the
引用名言式：用一个相关的谚语、术语、名言或名人实例来引题。
Just as the saying goes,
The saying that comes to me at the first sight of this topic.
在引题时要注意不要照抄原题， 而且篇幅不宜过长，在引题之后，迅速进入自己所支持的观点，或表态，并引起下文。
论述L详细阐述分支观点的部分，在开题首段的第二句一般是文章的主旨句所在，而在论述部分的理由段中，各个分论点应该放在首句的位置，开门见山。