Some people think / believe that ...

They are for the opinion that ...

... percent of people think it necessary to ...

The reason is that ...

★介绍反方观点：

However / On the other hand, ... of people think that ...

However / On the other hand, others think quite differently.

Others argue that ...

The reasons are as follows.

★提出自己的观点：

As far as I'm concerned / In my opinion, I firmly support the opinion that ...

It's my opinion that ...

My opinion is that ...

In a word / In conclusion, ...

【参考范文】

　　Today, our class had a discussion about whether it is necessary for middle school students to read English original classics. Different students have different opinions.

　　Many of us are for the idea. Firstly, they think by reading classics we can enlarge our vocabulary and improve our writing skills. What's more, it is a good way for us to learn more about western history and culture. However, others don't think so. In their opinion, with a busy studying schedule, we can hardly find extra time to read great English works of literature. Besides, because of the limited vocabulary we have, we may find English classics difficult to understand.

　　In my opinion, classics are examples of great writing and wisdom, and we should try to read some classics whenever possible.