Could / would you please elaborate more?

You mean that........?

I don't understand what you mean.

Polite way of saying "Please tell me/ us..........."

As far as I know,

In my opinion,

I think that, what I think is that

What is your opinion about this?

How do you assess / interpret. this issue?

It is exactly like this.

You are absolutely right.

I agree with you, to some extent.

Unfortunately, I do not agree with you at all.

I understand what you are saying, but

I am not sure if...

What is the reason?

This causes that