Divide the elements into the groups

In my opinion, Personally, I think, I believe that, It is clear to me that, It seems to me that, From my point of view, I am sure, I (dis)agree with the statement because, My main reason is, One reason for… is, Because, Since, Because of, Due to, It is a well-known fact that, It is a fact that, It is clear, It's true that, For example, For instance

To express opinion	To give reasons	To express facts

Moreover, In addition to, Furthermore, Firstly, Secondly, Thirdly, Lastly, Finally, Despite, In spite of, However, Whereas, On the one hand, On the other hand, To sum up, To conclude, In conclusion

To add ideas	To express contrast	To conclude